Data Handling

Multiple Choice Questions

Question 1

Which of the following are valid Python data types ?

1. Numeric
2. None ✓
3. Mappings
4. list ✓
5. Sequence
6. set ✓
7. tuple ✓
8. dictionary ✓

Question 2

Which of the following are datatypes considered as Numbers in Python.

1. Integer ✓
2. Boolean ✓
3. complex ✓
4. floating point ✓
5. list
6. None

Question 3

Consider the following sequence of statements:
a = 35
m = a
Following the execution of these statements, Python has created how many objects and how many references ?

1. Two integer objects, two references
2. One integer object, two references ✓
3. One integer object, one reference
4. Two integer objects, one reference

Question 4

Which Python built-in function returns the unique number assigned to an object?

1. identity( )
2. id( ) ✓
3. refnum( )
4. ref( )

Question 5

The operator used to check if both the operands reference the same object memory, is the .......... operator.

1. in
2. is ✓
3. id
4. ==

Question 6

For two objects x and y, the expression x is y will yield True, if and only if

1. id(x) == id(y) ✓
2. len(x) == len(y)
3. x == y
4. all of these

Question 7

Which of the following is not an immutable type in Python ?

1. String
2. Tuples
3. Set ✓
4. dictionary ✓

Question 8

Python operator always yields the result of .......... datatype.

1. integer
2. floating point ✓
3. complex
4. all of these

Question 9

What is the value of the expression 100 / 25 ?

1. 4
2. 4.0 ✓
3. 2.5
4. none of these

Question 10

What is the value of the expression 100 // 25 ?

1. 4 ✓
2. 4.0
3. 2.5
4. none of these

Question 11

In Python, a variable must be declared before it is assigned a value.

1. True
2. False ✓
3. Only in Functions
4. Only in modules

Question 12

In Python, a variable is assigned a value of one type, and then later assigned a value of a different type. This will yield .......... .

1. Warning
2. Error
3. None
4. No Error ✓

Question 13

In Python, a variable may be assigned a value of one type, and then later assigned a value of a different type. This concept is known as .......... .

1. mutability
2. static typing
3. dynamic typing ✓
4. immutability

Question 14

Is it safe to directly use the == operator to determine whether objects of type float are equal ?

1. Yes
2. No ✓
3. Yes, if the values are < 100
4. Yes, if the values are > 100

Question 15

What will the following code produce ?

a = 8.6
b = 2
print ( a//b )

1. 4.3
2. 4.0 ✓
3. 4
4. compilation error

Question 16

In the Python statement x = a + 5 - b : a and b are .......... .

1. Operands ✓
2. Expression
3. operators
4. Equation

Question 17

In the Python statement x =a + 5 - b : a + 5 - b is .......... .

1. Operands
2. Expression ✓
3. operators
4. Equation

Question 18

What will be the value of y after following code fragment is executed ?

x = 10.0
y = (x < 100.0) and x >= 10

1. 110
2. True ✓
3. False
4. Error.

Question 19

Which of the following literals has True truth-value ?

1. 0.000001 ✓
2. 'None' ✓
3. 0
4. [ ]
5. False
6. True ✓
7. 1 ✓
8. 33 ✓
9. None
10. 0.0

Question 20

What will the following code result as ?

import math
x = 100
print ( x > 0 and math.sqrt( x ) )

1. True
2. 1
3. 10
4. 10.0 ✓

Question 21

Which of the following operators has the lowest precedence ?

1. not
2. %
3. and ✓
4. +
5. **

Question 22

What is the value of the expression 10 + 3 ** 3 * 2?

1. 28
2. 739
3. 829
4. 64 ✓

Question 23

To increase the value of x five times using an augmented assignment operator, the correct expression will be

1. x += 5
2. x *= 5 ✓
3. x = x ** 5
4. none of these

Question 24

What will be the result of the expression 10 or 0 ?

1. 0
2. 1
3. 10 ✓
4. 1.0

Question 25

What will be the result of the expression 5 or 10 ?

1. 5 ✓
2. 1
3. 10
4. 0

Question 26

What will be the result of the expression 5 and 10?

1. 5
2. 1
3. 10 ✓
4. 0

Question 27

What will be the result of the expression 15 and 10?

1. 5
2. 1
3. 10 ✓
4. 0

Question 28

What will be the result of the expression 10 or 0 ?

1. 0
2. 1
3. 10 ✓
4. 1.0

Question 29

What will be the result of the expression 'a' or " (" is an empty string) ?

1. 'a' ✓
2. "
3. 1
4. 0

Question 30

What will be the result of the expression 'a' and " (" is an empty string) ?

1. 'a'
2. " ✓
3. 1
4. 0

Question 31

What will be the result of the expression 'x' and 'a' ?

1. 'a' ✓
2. "
3. 'x'
4. 1

Question 32

What will be the result of the expression 'a' and 'x' ?

1. 'a'
2. ''
3. 'x' ✓
4. 1

Question 33

What will be the result of the expression 'a' and 'None' ?

1. 'a'
2. ''
3. 'None' ✓
4. 1

Question 34

What will be the result of the expression 'None' and 'a' ?

1. 'a' ✓
2. ''
3. 'None'
4. 1

Question 35

What will be the result of the expression 'false' and False ?

1. false
2. False ✓
3. 'false'
4. 'False'

Question 36

What will be the result of the expression 'false' or False ?

1. false
2. False
3. 'false' ✓
4. 'False'

Fill in the Blanks

Question 1

Boolean data type is internally treated as integer data type.

Question 2

Two forms of floating-point numbers are: fractional form and exponent notation.

Question 3

Python's floating point numbers have precision of 15 digits.

Question 4

Three mutable types of Python are lists, dictionaries and sets.

Question 5

The floor division of two integers yields a result of integer type.

Question 6

The division of two integers yields a result of floating-point type.

Question 7

The set sequence type cannot store duplicate values.

Question 8

The tuple datatype is like lists but is not mutable.

Question 9

The id of an object gives the memory location of the object.

Question 10

To check if two objects reference the same memory address, is operator is used.

Question 11

To use function fabs( ), math module should be imported.

Question 12

To generate a random floating number in the range 0 to 100, random() or random.random() function is used.

Question 13

To generate a random integer in a range, randint() or random.randint() function is used.

Question 14

To generate a random number in a sequence of values where two values have a difference a step value, randrange() or random.randrange() function is used.

Question 15

To use mean() function, statistics module is to be imported.

True/False Questions

Question 1

List is an immutable data type.
False

Question 2

Set is a mutable data type.
True

Question 3

A set can contain duplicate values in it.
False

Question 4

A Boolean value is internally treated as an integer value.
True

Question 5

'' (an empty string) has truth value as False.
True

Question 6

' ' (a space) has truth value as False.
False

Question 7

Value false is a legal literal value in Python.
False

Question 8

Value False is a legal literal value in Python.
True

Question 9

Value 'False' is a legal literal value in Python.
True

Question 10

Value 'false' is a legal literal value in Python.
True

Question 11

None and 'None' are the same.
False

Question 12

None has the truth value as False.
True

Question 13

'None' has the truth value as False.
False

Question 14

The result of bool(0) is False.
True

Question 15

The result of bool('None') is False.
False

Question 16

Dividing two integers results in an integer.
False

Question 17

Floor division of two integers results in an integer.
True

Question 18

Two floating point numbers should not be compared for equality using ==
True

Question 19

In implicit conversion, all operands' data types are converted to the datatype of the largest operand.
True

Question 20

Explicit type conversion involves the use of a function to convert datatype of a value.
True

Type A: Short Answer Questions/Conceptual Questions

Question 1

What are data types in Python? How are they important?

Answer

Data types are used to identify the type of data a memory location can hold and the associated operations of handling it. The data that we deal with in our programs can be of many types like character, integer, real number, string, boolean, etc. hence programming languages including Python provide ways and facilities to handle all these different types of data through data types. The data types define the capabilities to handle a specific type of data such as memory space it allocates to hold a certain type of data and the range of values supported for a given data type, etc.

Question 2

How many integer types are supported by Python? Name them.

Answer

Two integer types are supported by Python. They are:

1. Integers (signed)
2. Booleans

Question 3

How are these numbers different from one another (with respect to Python)? 33, 33.0, 33j, 33 + j

Answer

The number 33 is an integer whereas 33.0 is a floating-point number. 33j represent the imaginary part of a complex number. 33 + j is a complex number.

Question 4

The complex numbers have two parts : real and imaginary. In which data type are real and imaginary parts represented ?

Answer

In Python, the real and imaginary parts of a complex number are represented as floating-point numbers.

Question 5

How many string types does Python support? How are they different from one another?

Answer

Python supports two types of strings — Single-line strings and Multi-line strings. Single line strings are enclosed in single or double quotes and terminate in one line. Multi-line strings store multiple lines of text and are enclosed in triple quotes.

Question 6

What will following code print?

str1 = '''Hell
o'''
str2 = '''Hell\
o'''
print(len(str1) > len(str2))

Answer

This code will print:

True

len(str1) is 6 due to the EOL character. len(str2) is 5 as backslash (\) character is not counted in the length of string. As len(str1) is greater than len(str2) so the output is True.

Question 7

What are Immutable and Mutable types in Python? List immutable and mutable types of Python.

Answer

Mutable types are those whose values can be changed in place whereas Immutable types are those that can never change their value in place.

Mutable types in Python are:

1. Lists
2. Dictionaries
3. Sets

Immutable types in Python are:

1. Integers
2. Floating-Point numbers
3. Booleans
4. Strings
5. Tuples

Question 8

What are three internal key-attributes of a value-variable in Python ? Explain with example.

Answer

The three internal key-attributes of a value-variable in Python are:

1. Type
2. Value
3. Id

For example, consider this:

a = 4

The type of a is int which can be found with the built-in function type() like this:
type(a).

Value can be found using the built-in function print() like this:
print(a)

It will give the output as 4 which is value contained in variable a.

Id is the memory location of the object which can be determined using built-in function id() like this:
id(a)

Question 9

Is it true that if two objects return True for is operator, they will also return True for == operator?

Answer

Yes, if is operator returns true, it implicitly means that the equality operator will also return True. is operator returning true implies that both the variables point to the same object and hence == operator must return True.

Question 10

Are these values equal? Why/why not?

1. 20 and 20.0
2. 20 and int(20)
3. str(20) and str(20.0)
4. 'a' and "a"

Answer

1. The type of 20 is int whereas the type of 20.0 is float so they are two different objects. Both have the same value of 20. So, as values are same equality (==) operator return True but as objects are different is operator returns False.
2. The value and type of both 20 and int(20) are the same and both point to the same object so both equality (==) and is operator returns True.
3. For str(20) and str(20.0), both equality (==) and is operator returns False as their values are different and they point to two different objects.
4. For 'a' and "a", both equality (==) and is operator returns True as their values are same and they point to the same object.

Question 11

What is an atom in Python? What is an expression?

Answer

In Python, an atom is something that has a value. Identifiers, literals, strings, lists, tuples, sets, dictionaries, etc. are all atoms. An expression in Python, is any valid combination of operators and atoms. It is composed of one or more operations.

Question 12

What is the difference between implicit type conversion and explicit type conversion?

Answer

Question 13

Two objects (say a and b) when compared using == ,return True. But Python gives False when compared using is operator. Why? (i.e., a == b is True but why is a is b False?)

Answer

As equality (==) operator returns True, it means that a and b have the same value but as is operator returns False, it means that variables a and b point to different objects in memory. For example, consider the below Python statements:

>>> a = 'abc'
>>> b = input("Enter a string: ")
Enter a string: abc
>>> a == b
True
>>> a is b
False

Here, both a and b have the same value 'abc' but they point to different objects.

Question 14

Given str1 = "Hello", what will be the values of:

(a) str1[0]

(b) str1[1]

(c) str1[-5]

(d) str1[-4]

(e) str1[5]

Answer

(a) H

(b) e

(c) H

(d) e

(e) IndexError: string index out of range

Explanation

$\begin{matrix} \underset{-5}{\overset{0}{\bold{H}}} & \underset{-4}{\overset{1}{\bold{e}}} & \underset{-3}{\overset{2}{\bold{l}}} & \underset{-2}{\overset{3}{\bold{l}}} & \underset{-1}{\overset{4}{\bold{o}}} \end{matrix}$

Question 15

If you give the following for str1 = "Hello", why does Python report error?

str1[2] = 'p'

Answer

Python reports error because strings are immutable and hence item assignment is not supported.

Question 16

What will the result given by the following?

(a) type (6 + 3)

(b) type (6 -3)

(c) type (6 *3)

(d) type (6 / 3)

(e) type (6 // 3)

(f) type (6 % 3)

Answer

(a) type (6 + 3)
⇒ int + int
⇒ int
So the result is int.

(b) type (6 -3)
⇒ int - int
⇒ int
So the result is int.

(c) type (6 * 3)
⇒ int * int
⇒ int
So the result is int.

(d) type (6 / 3)
⇒ int / int
⇒ float
So the result is float.

(e) type (6 // 3)
⇒ int // int
⇒ int
So the result is int.

(f) type (6 % 3)
⇒ int % int
⇒ int
So the result is int.

Question 17

What are augmented assignment operators? How are they useful?

Answer

Augmented assignment operators combine the impact of an arithmetic operator with an assignment operator. For example, to add the value of b to the value of a and assign the result back to a then instead of writing:

a = a + b

we can write

a += b.

Augmented assignment operators are useful as they provide a shorthand way by combining the arithmetic and assignment operators.

Question 18

Differentiate between (555/222)**2 and (555.0/222)**2.

Answer

In the first expression, 555 is of int type whereas in the second expression 555.0 is of float type.

Question 19

Given three Boolean variables a, b, c as : a = False, b = True, c = False. Evaluate the following Boolean expressions:

(a) b and c

(b) b or c

(c) not a and b

(d) (a and b) or not c

(e) not b and not (a or c)

(f) not ((not b or not a) and c) or a

Answer

(a) b and c
     ⇒ False and True
     ⇒ False

(b) b or c
     ⇒ True or False
     ⇒ True

(c) not a and b
     ⇒ not False and True
     ⇒ True and True
     ⇒ True

(d) (a and b) or not c
     ⇒ (False and True) or not False
     ⇒ False or not False
     ⇒ False or True
     ⇒ True

(e) not b and not (a or c)
     ⇒ not True and not (False or False)
     ⇒ not True and not False
     ⇒ False and True
     ⇒ False

(f) not ((not b or not a) and c) or a
     ⇒ not ((not True or not False) and False) or False
     ⇒ not ((False or True) and False) or False
     ⇒ not (True and False) or False
     ⇒ not False or False
     ⇒ True or False
     ⇒ True

Question 20

What would following code fragments result in? Given x = 3.

(a) 1 < x

(b) x >= 4

(c) x == 3

(d) x == 3.0

(e) "Hello" == "Hello"

(f) "Hello" > "hello"

(g) 4/2 == 2.0

(h) 4/2 == 2

(i) x < 7 and 4 > 5.

Answer

(a) True

(b) False

(c) True

(d) True

(e) True

(f) False

(g) True

(h) True

(i) False

Question 21

Write following expressions in Python:

(a) $\dfrac{1}{3} b^2 h$

Answer

1 / 3 * b * b * h

(b) $\pi r^2 h$

Answer

math.pi * r * r * h

(c) $\dfrac{1}{3} \pi r^2 h$

Answer

1 / 3 * math.pi * r * r * h

(d) $\sqrt{(x2 - x1)^2 + (y2 - y1)^2}$

Answer

math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)

(e) $(x - h)^2 + (y - k)^2 = r^2$

Answer

(x - h) ** 2 + (y - k) ** 2 == r ** 2

(f) $x = \dfrac{-b + \sqrt{b^2 - 4ac}}{2a}$

Answer

x = (-b + math.sqrt(b * b - 4 * a * c)) / (2 * a)

(g) $a^n \times a^m = a^{n+m}$

Answer

a ** n * a ** m == a ** (n + m)

(h) $(a^n)^m = a^{nm}$

Answer

(a ** n) ** m == a ** (n * m)

(i) $\dfrac{a^n}{a^m} = a^{n - m}$

Answer

a ** n / a ** m == a ** (n - m)

(j) $a^{-n} = \dfrac{1}{a^n}$

Answer

a ** -n == 1 / a ** n

Question 22

int('a') produces error. Why ?

Answer

int() converts its argument into an integer. As 'a' is a letter, it cannot be converted into a valid integer hence int('a') produces an error.

Question 23

int('a') produces error but following expression having int('a') in it, does not return error. Why?

len('a') + 2 or int('a')

Answer

The or operator tests the second operand only if the first operand is false otherwise it ignores it. In the expression, the first operand of or operator is len('a') + 2. It evaluates to 3 and as it is a non-zero value hence it is True for or operator. As first operand of or operator is True so it doesn't evaluate its second argument int('a') and no error is returned.

Question 24

Write expression to convert the values 17, len('ab') to (i) integer (ii) str (iii) boolean values

Answer

(i) int(17), int(len('ab'))

(ii) str(17), str(len('ab'))

(iii) bool(17), bool(len('ab'))

Question 25

Evaluate and Justify:

(i) 22 / 17 = 37 / 47 + 88 /83

(ii) len('375')**2

Answer

(i) It produces an error as LHS value in this case is an expression that evaluates to a literal whereas LHS value should be a variable.

(ii) len('375')**2
 ⇒ 3 ** 2    [∵ len('375') = 3]
 ⇒ 9           [∵ 3 * 3 = 9]

Question 26

Evaluate and Justify:

(i) 22.0/7.0 - 22/7

(ii) 22.0/7.0 - int(22.0/7.0)

(iii) 22/7 - int (22.0)/7

Answer

(i) 22.0/7.0 - 22/7
 ⇒ 0

As values of 22.0/7.0 and 22/7 are equal, subtracting them will give the result as 0.0.

(ii) 22.0/7.0 - int(22.0/7.0)
 ⇒ 3.142857142857143 - 3
 ⇒ 0.142857142857143

(iii) 22/7 - int (22.0)/7
 ⇒ 0.0

int (22.0) gives 22 so the expression becomes 22/7 - 22/7 which results in 0.0

Question 27

Evaluate and Justify:

(i) false and None

(ii) 0 and None

(iii) True and None

(iv) None and None

Answer

(i) This produces an error as false is an invalid literal in Python. It should be False. Had the expression being False and None, the return value will be False.

(ii) This logical expression evaluates to 0. As first operand of and operator is false so it will return the first operand itself.

(iii) This logical expression evaluates to None. As first operand of and operator is True so it will return the second operand.

(iv) This logical expression evaluates to None. As first operand of and operator is false so it will return the first operand itself.

Question 28

Evaluate and Justify:

(a) 0 or None and "or"

(b) 1 or None and 'a' or 'b'

(c) False and 23

(d) 23 and False

(e) not (1 == 1 and 0 != 1)

(f) "abc" == "Abc" and not (2 == 3 or 3 == 4)

(g) False and 1 == 1 or not True or 1 == 1 and False or 0 == 0

Answer

(a) 0 or None and "or"
 ⇒ 0 or None   [∵ and has higher precedence than or]
 ⇒ None

(b) 1 or None and 'a' or 'b'
 ⇒ 1 or None or 'b'
 ⇒ 1 or 'b'
 ⇒ 1

(c) False and 23
 ⇒ False

(d) 23 and False
 ⇒ False

(e) not (1 == 1 and 0 != 1)
 ⇒ not (True and True)
 ⇒ not True
 ⇒ False

(f) "abc" == "Abc" and not (2 == 3 or 3 == 4)
 ⇒ "abc" == "Abc" and not (False or False)
 ⇒ "abc" == "Abc" and not False
 ⇒ False and not False
 ⇒ False and True
 ⇒ False

(g) False and 1 == 1 or not True or 1 == 1 and False or 0 == 0
 ⇒ False and True or not True or True and False or True
 ⇒ False and True or False or True and False or True
 ⇒ False or False or False or True
 ⇒ False or False or True
 ⇒ False or True
 ⇒ True

Question 29

Evaluate the following for each expression that is successfully evaluated, determine its value and type for unsuccessful expression, state the reason.

(a) len("hello") == 25/5 or 20/10

(b) 3 < 5 or 50/(5 - (3 + 2))

(c) 50/(5 - (3 + 2)) or 3 < 5

(d) 2 * (2 * (len("01")))

Answer

(a) len("hello") == 25/5 or 20/10
 ⇒ 5 == 25/5 or 20/10
 ⇒ 5 == 5 or 2
 ⇒ True or 2
 ⇒ True

The type of result is Boolean.

(b) 3 < 5 or 50/(5 - (3 + 2))
 ⇒ True or 50/(5 - (3 + 2))   [∵ first operand is True, second operand is not evaluated so no division by 0 error happens]
 ⇒ True

The type of result is Boolean.

(c) 50/(5 - (3 + 2)) or 3 < 5
 ⇒ 50/(5 - 5) or 3 < 5
 ⇒ 50/0 or 3 < 5
 ⇒ Division by Zero Error

As the denominator of or operator's first operand is 0, Division by Zero error occurs.

(d) 2 * (2 * (len("01")))
 ⇒ 2 * (2 * 2)
 ⇒ 2 * 4
 ⇒ 8

The type of result is Integer.

Question 30

Write an expression that uses exactly 3 arithmetic operators with integer literals and produces result as 99.

Answer

9 * 10 + 21 % 12

Question 31

Add parentheses to the following expression to make the order of evaluation more clear.

y % 4 == 0 and y % 100 != 0 or y % 400 == 0

Answer

((y % 4) == 0) and ((y % 100) != 0) or ((y % 400) == 0)

Question 32

A program runs to completion but gives an incorrect result. What type of error would have caused it?

Answer

Logical errors can make a program run till completion but give incorrect result.

Question 33

In Python, strings are immutable while lists are mutable. What is the difference?

Answer

In Python, strings are immutable means that individual letter assignment for strings is not allowed. For example:

name='hello'
name[0] = 'p'

The above Python code will cause an error as we are trying to assign some value to an individual letter of a string.

Lists are mutable in Python means that we can assign values to individual elements of a list. For example:

a = [1, 2, 3, 4, 5]
a[0] = 10

The above Python code will work correctly without any errors as Lists are mutable in Python.

Question 34

How does the // operator differ from the / operator? Give an example of where // would be needed.

Answer

The Division operator (/) divides its first operand by second operand and always returns the result as a float value whereas Floor Division operator (//) divides its first operand by second operand and truncates the fractional part of the result and returns it as an int value. Floor Division operator is useful in situations where we only need the integer part of the division operation result. For example, to determine how many minutes are there in some given number of seconds:

secs = 2565
mins = 2565 // 60

Question 35

MidAir Airlines will only allow carry-on bags that are no more than 22 inches long, 14 inches wide, and 9 inches deep. Assuming that variables named length, width, and depth have already been assigned values, write an expression combining the three that evaluates to True if bag fits within those limits, and False otherwise.

Answer

length <= 22 and width <= 14 and depth <= 9

Question 36

What are main error types? Which types are most dangerous and why?

Answer

The types of errors are:

1. Compile Time Errors (Syntax errors and Semantic Errors)
2. Runtime Errors
3. Logical Errors

Logical Errors are the most dangerous as they are hardest to prevent, find and fix.

Question 37

Correct any false statements:

(a) Compile-time errors are usually easier to detect and to correct than run-time errors.

(b) Logically errors can usually be detected by the compiler.

Answer

(a) The statement is correct.

(b) The statement is incorrect. The correct statement should be:

Logical errors cannot be detected by the compiler.

Question 38

Differentiate between a syntax error and a semantics error.

Answer

Question 39

Differentiate between a syntax error and a logical error in a python program. When is each type of error likely to be found?

Answer

Syntax errors are found at compile type whereas Logical errors are found when the program starts executing.

Question 40

What is the difference between an error and exception?

Answer

An Error is a bug in the code that causes irregular output or stops the program from executing whereas an Exception is an irregular unexpected situation occurring during execution on which programmer has no control.

Type B: Application Based Questions

Question 1

What is the result produced by (i) bool (0) (ii) bool (str(0))? Justify the outcome.

Answer

(i) bool (0)

The result is False as truth value of 0 is false_tval

(ii) bool (str(0))

The result is True as str(0) converts 0 to string "0". As it becomes a non-empty string so its truth value is true_tval

Question 2

What will be the output, if input for both the statements is 5 + 4/2.

6 == input ("Value 1:")
6 == int(input ("value 2:"))

Answer

Output of first statement is False as '5 + 4/2' is entered as a string so it cannot be equal to the number 6.

The second statement gives an error as int() function cannot convert the string '5 + 4/2' to a valid integer.

Question 3

Following Python code has an expression with all integer values. Why is the result in floating point form?

a, b, c = 2, 3, 6
d = a + b * c/b
print(d)

Answer

The output of the above Python code is 8.0. Division operator is present in the expression. The result of Division operator is of float type. Due to implicit conversion, other operand in this expression are also converted to float type and hence the final result is in floating point form.

Question 4a

What will following code print?

a = va = 3  
b = va = 3  
print (a, b)

Answer

This Python code prints:

3 3

Question 4b

What will following code print?

a = 3
b = 3.0
print (a == b)
print (a is b)

Answer

This Python code prints:

True
False

As values of a and b are equal so equality operator returns True. a is of int type and b is of float type so a and b are different objects so a is b returns False.

Question 5a

What will be output produced by following code? State reason for this output.

a, b, c = 1, 1, 2
d = a + b
e = 1.0
f = 1.0
g = 2.0
h = e + f
print(c == d)
print(c is d)
print(g == h)
print(g is h)

Answer

Output

True
True
True
False

Explanation

Value of d becomes 2 and as values of c and d are equal so print(c == d) prints True.

Question 5b

What will be output produced by following code? State reason for this output.

a = 5 - 4 - 3
b = 3**2**3  
print(a)     
print(b)     

Answer

Output

-2
6561

Explanation

    a = 5 - 4 - 3
⇒ a = 1 - 3
⇒ a = -2

The exponentiation operator (**) has associativity from right to left so:

    b = 3**2**3
⇒ b = 3**8
⇒ b = 6561

Question 5c

What will be output produced by following code? State reason for this output.

a, b, c = 1, 1, 1
d = 0.3
e=a+b+c-d
f=a+b+c == d
print(e)
print(f)

Answer

Output

2.7
False

Explanation

    e = a+b+c-d
⇒ e = 1+1+1-0.3
⇒ e = 3-0.3
⇒ e = 2.7

As 0.3 is float so implicit conversion converts 3 also to float and result of the expression is of float type.

    f = a + b + c == d
⇒ f = 1 + 1 + 1 == 0.3
⇒ f = 3 == 0.3
⇒ f = False

Question 6a

What will be the output of following Python code?

a = 12     
b = 7.4     
c = 1       
a -= b
print(a, b)
a *= 2 + c
print(a)
b += a * c
print(b)

Answer

Output

4.6 7.4
13.799999999999999
21.2

Explanation

    a -= b
⇒ a = a - b
⇒ a = 12 - 7.4
⇒ a = 4.6

    a *= 2 + c
⇒ a = 4.6 * (2 + c)
⇒ a = 4.6 * (2 + 1)
⇒ a = 4.6 * 3
⇒ a = 13.799999999999999

    b += a * c
⇒ b = b + (a * c)
⇒ b = 7.4 + (13.799999999999999 * 1)
⇒ b = 7.4 + 13.799999999999999
⇒ b = 21.2

Question 6b

What will be the output of following Python code?

x, y = 4, 8
z = x/y*y 
print(z)

Answer

Output

4.0

Explanation

    z = x/y*y
⇒ z = 4/8*8
⇒ z = 0.5*8
⇒ z = 4.0

Question 7

Make change in the expression for z of previous question so that the output produced is zero. You cannot change the operators and order of variables. (Hint. Use a function around a sub-expression)

Answer

x, y = 4, 8
z = int(x/y)*y 
print(z)

Question 8

Consider the following expression:

x = "and" * (3 + 2) > "or" + "4"

What is the data type of value that is computed by this expression?

Answer

The data type of value that is computed by this expression is bool.

    x = "and" * (3 + 2) > "or" + "4"
⇒ x = "and" * 5 > "or" + "4"
⇒ x = "andandandandand" > "or4"
⇒ x = False

Question 9

Consider the following code segment:

a = input()
b = int(input())
c = a + b 
print(c)

When the program is run, the user first enters 10 and then 5, it gives an error. Find the error, its reason and correct it

Answer

The error is:

TypeError: can only concatenate str (not "int") to str

It occurs because a is of type string but b is of type int. We are trying to add together a string operand and an int operand using addition operator. This is not allowed in Python hence this error occurs.

To correct it, we need to cast a to int like this:

a = int(input())

Question 10

Consider the following code segment:

a = input("Enter the value of a:")
b = input("Enter the value of b:")
print(a + b)

If the user runs the program and enters 11 for a and 9 for b then what will the above code display?

Answer

Output

Enter the value of a:11
Enter the value of b:9
119

Explanation

input() function accepts user input as string type. The data type of a and b is string not int so addition operator concatenates them to print 119 instead of 20.

Question 11

Find out the error and the reason for the error in the following code. Also, give the corrected code.

a, b = "5.0", "10.0"
x = float(a/b)
print(x)

Answer

a and b are defined as strings not float or int. Division operator doesn't support strings as its operand so we get the error — unsupported operand type(s) for /: "str" and "str".

The corrected code is:

a, b = 5.0, 10.0
x = float(a/b)
print(x)

Question 12

Consider the following program. It is supposed to compute the hypotenuse of a right triangle after the user enters the lengths of the other two sides.

a = float(input("Enter the length of the first side:"))
b = float(input("Enter the length of the second side:"))
h = sqrt(a * a + b * b)
print("The length of the hypotenuse is", h)

When this program is run, the following output is generated (note that input entered by the user is shown in bold):

Enter the length of the first side: 3
Enter the length of the second side: 4
Traceback (most recent call last):
h = sqrt(a * a + b * b)
NameError: name 'sqrt' is not defined

Why is this error occurring? How would you resolve it ?

Answer

The error is coming because math module is not imported in the code. To resolve it, we should import the math module using the import statement import math.

Question 13

Consider the following program. It is supposed to compute the hypotenuse of a right triangle after the user enters the lengths of the other two sides.

a = float(input("Enter the length of the first side:"))
b = float(input("Enter the length of the second side:"))
h = sqrt(a * a + b * b)
print("The length of the hypotenuse is", h)

After adding import math to the code given above, what other change(s) are required in the code to make it fully work ?

Answer

After adding import math statement, we need to change the line h = sqrt(a * a + b * b) to h = math.sqrt(a * a + b * b). The corrected working code is below:

import math
a = float(input("Enter the length of the first side:"))
b = float(input("Enter the length of the second side:"))
h = math.sqrt(a * a + b * b)
print("The length of the hypotenuse is", h)

Question 14

Which of the following expressions will result in an error message being displayed when a program containing it is run?

(a) 2.0/4

(b) "3" + "Hello"

(c) 4 % 15

(d) int("5")/float("3")

(e) float("6"/"2")

Answer

(a) No Error

(b) No Error

(c) No Error

(d) No Error

(e) This will cause an error of unsupported operand types as using division operator on string types is not allowed in Python.

Question 15a

Following expression does not report an error even if it has a sub-expression with 'divide by zero' problem:

3 or 10/0

What changes can you make to above expression so that Python reports this error?

Answer

Interchanging the operands of or operator as shown below will make Python report this error:

10/0 or 3

Question 15b

What is the output produced by following code?

a, b = bool(0), bool(0.0)
c, d = str(0), str(0.0) 
print (len(a), len(b)) 
print (len(c), len(d))

Answer

The above code will give an error as the line print (len(a), len(b)) is calling len function with bool arguments which is not allowed in Python.

Question 16

Given a string s = "12345". Can you write an expression that gives sum of all the digits shown inside the string s i.e., the program should be able to produce the result as 15 (1+2+3+4+5).
[Hint. Use indexes and convert to integer]

Answer

print(int(s[0]) + int(s[1]) + int(s[2]) + int(s[3]) + int(s[4]))

Question 17

Predict the output if e is given input as 'True':

a = True
b = 0 < 5
print (a == b) 
print (a is b)
c = str (a)
d = str (b)
print (c == d) 
print (c is d)
e = input ("Enter :")
print (c == e) 
print (c is e)

Answer

Output

True
True
True
True
Enter :True
True
False

Explanation

1. As 0 < 5 is True so b value of b becomes True and its type is bool.
2. print (a == b) gives True as a and b both are True.
3. print (a is b) gives True as a and b both being True point to the same object in memory.
4. Similarly print (c == d) and print (c is d) give True as c and d both are string and point to the same object in memory.
5. The user input for e is True so e is of type string having value "True".
6. As value of strings c and e is "True" so print (c == e) gives True.
7. Even though the values of strings c and e are same, they point to different objects in memory so print (c is e) gives False.

Question 18a

Find the errors(s)

name = "HariT"
print (name)  
name[2] = 'R' 
print (name)  

Answer

The line name[2] = 'R' is trying to assign the letter 'R' to the second index of string name but strings are immutable in Python and hence such item assignment for strings is not supported in Python.

Question 18b

Find the errors(s)

a = bool (0) 
b = bool (1) 
print (a == false)
print (b == true)

Answer

false and true are invalid literals in Python. The correct boolean literals are False and True.

Question 18c

Find the errors(s)

print (type (int("123")))  
print (type (int("Hello")))
print (type (str("123.0")))

Answer

In the line print (type (int("Hello"))), string "Hello" is given as an argument to int() but it cannot be converted into a valid integer so it causes an error.

Question 18d

Find the errors(s)

pi = 3.14
print (type (pi))
print (type ("3.14"))
print (type (float ("3.14")))
print (type (float("three point fourteen")))

Answer

In the line print (type (float("three point fourteen"))), string "three point fourteen" is given as an argument to float() but it cannot be converted into a valid floating-point number so it causes an error.

Question 18e

Find the errors(s)

print ("Hello" + 2)  
print ("Hello" + "2")
print ("Hello" * 2) 

Answer

The line print ("Hello" + 2) causes an error as addition operator (+) cannot concatenate a string and an int.

Question 18f

Find the errors(s)

print ("Hello"/2) 
print ("Hello" / 2)

Answer

Both the lines of this Python code will give an error as strings cannot be used with division operator (/).

Question 19a

What will be the output produced?

x, y, z = True, False, False
a = x or (y and z)           
b = (x or y) and z           
print(a, b)

Answer

Output

True False

Explanation

1. x or (y and z)
   ⇒ True or (False and False)
   ⇒ True
2. (x or y) and z
   ⇒ (True or False) and False
   ⇒ True and False
   ⇒ False

Question 19b

What will be the output produced?

x, y = '5', 2
z = x + y
print(z)

Answer

This code produces an error in the line z = x + y as operands of addition operator (+) are string and int, respectively which is not supported by Python.

Question 19c

What will be the output produced?

s = 'Sipo'  
s1 = s + '2'
s2 = s * 2  
print(s1) 
print(s2)

Answer

Output

Sipo2
SipoSipo

Explanation

1. s1 = s + '2' concatenates 'Sipo' and '2' storing 'Sipo2' in s1.
2. s2 = s * 2 repeats 'Sipo' twice storing 'SipoSipo' in s2.

Question 19d

What will be the output produced?

w, x, y, z = True , 4, -6, 2
result = -(x + z) < y or x ** z < 10
print(result)

Answer

Output

False

Explanation

    -(x + z) < y or x ** z < 10
⇒ -(4 + 2) < -6 or 4 ** 2 < 10
⇒ -6 < -6 or 4 ** 2 < 10
⇒ -6 < -6 or 16 < 10
⇒ False or False
⇒ False

Question 20

Program is giving a weird result of "0.50.50.50.50.50.50..........". Correct it so that it produces the correct result which is the probability value (input as 0.5) times 150.

probability = input("Type a number between 0 and 1: ")
print("Out of 150 tries, the odds are that only", (probability * 150), "will succeed.")

[Hint. Consider its datatype.]

Answer

The corrected program is below:

probability = float(input("Type a number between 0 and 1: "))
print("Out of 150 tries, the odds are that only", (probability * 150), "will succeed.")

Question 21

Consider the code given below:

import random
r = random.randrange(100, 999, 5)
print(r, end = ' ')
r = random.randrange(100, 999, 5)
print(r, end = ' ')
r = random.randrange(100, 999, 5)
print(r)

Which of the following are the possible outcomes of the above code ? Also, what can be the maximum and minimum number generated by line 2 ?

(a) 655, 705, 220
(b) 380, 382, 505
(c) 100, 500, 999
(d) 345, 650, 110

Answer

The possible outcomes of the above code can be:

Option (a) — 655, 705, 220
Option (d) — 345, 650, 110

Maximum number can be 995 and minimum number can be 100.

Question 22

Consider the code given below:

import random
r = random.randint(10, 100) - 10
print(r, end = ' ')
r = random.randint(10, 100) - 10
print(r, end = ' ')
r = random.randint(10, 100) - 10
print(r)

Which of the following are the possible outcomes of the above code? Also, what can be the maximum and minimum number generated by line 2?

(a) 12 45 22
(b) 100 80 84
(c) 101 12 43
(d) 100 12 10

Answer

The possible outcomes of the above code can be:

Option (a) — 12 45 22

Maximum number can be 90 and minimum number can be 0.

Question 23

Consider the code given below:

import random
r = random.random() * 10
print(r, end = ' ')
r = random. random() * 10
print(r, end = ' ')
r = random.random() * 10
print(r)

Which of the following are the possible outcomes of the above code? Also, what can be the maximum and minimum number generated by line 2 ?

(a) 0.5 1.6 9.8
(b) 10.0 1.0 0.0
(c) 0.0 5.6 8.7
(d) 0.0 7.9 10.0

Answer

The possible outcomes of the above code can be:

Option (a) — 0.5 1.6 9.8
Option (c) — 0.0 5.6 8.7

Maximum number can be 9.999999..... and minimum number can be 0.

Question 24

Consider the code given below:

import statistics as st
v = [7, 8, 8, 11, 7, 7]
m1 = st.mean(v)
m2 = st.mode(v)
m3 = st.median(v)
print(m1, m2, m3)

Which of the following is the correct output of the above code?

(a) 7 8 7.5
(b) 8 7 7
(c) 8 7 7.5
(c) 8.5 7 7.5

Answer

The correct output of the above code is:

Option (c) — 8 7 7.5

Type C: Programming Practice/Knowledge based Questions

Question 1

Write a program to obtain principal amount, rate of interest and time from user and compute simple interest.

Solution

p = float(input("Enter principal: "))
r = float(input("Enter rate: "))
t = float(input("Enter time: "))

si = p * r * t / 100

print("Simple Interest =", si)

Output

Enter principal: 55000.75
Enter rate: 14.5
Enter time: 3
Simple Interest = 23925.32625

Question 2

Write a program to obtain temperatures of 7 days (Monday, Tuesday ... Sunday) and then display average temperature of the week.

Solution

d1 = float(input("Enter Sunday Temperature: "))
d2 = float(input("Enter Monday Temperature: "))
d3 = float(input("Enter Tuesday Temperature: "))
d4 = float(input("Enter Wednesday Temperature: "))
d5 = float(input("Enter Thursday Temperature: "))
d6 = float(input("Enter Friday Temperature: "))
d7 = float(input("Enter Saturday Temperature: "))

avg = (d1 + d2 + d3 + d4 + d5 + d6 + d7) / 7

print("Average Temperature =", avg)

Output

Enter Sunday Temperature: 21.6
Enter Monday Temperature: 22.3
Enter Tuesday Temperature: 24.5
Enter Wednesday Temperature: 23.0
Enter Thursday Temperature: 23.7
Enter Friday Temperature: 24.2
Enter Saturday Temperature: 25
Average Temperature = 23.47142857142857

Question 3

Write a program to obtain x, y, z from user and calculate expression : 4x⁴ + 3y³ + 9z + 6π

Solution

import math

x = int(input("Enter x: "))
y = int(input("Enter y: "))
z = int(input("Enter z: "))

res = 4 * x ** 4 + 3 * y ** 3 + 9 * z + 6 * math.pi

print("Result =", res)

Output

Enter x: 2
Enter y: 3
Enter z: 5
Result = 208.84955592153875

Question 4

Write a program that reads a number of seconds and prints it in form : mins and seconds, e.g., 200 seconds are printed as 3 mins and 20 seconds.
[Hint. use // and % to get minutes and seconds]

Solution

totalSecs = int(input("Enter seconds: "))

mins = totalSecs // 60
secs = totalSecs % 60

print(mins, "minutes and", secs, "seconds")

Output

Enter seconds: 200
3 minutes and 20 seconds

Question 5

Write a program to take year as input and check if it is a leap year or not.

Solution

y = int(input("Enter year to check: "))
print(y % 4 and "Not a Leap Year" or "Leap Year")

Output

Enter year to check: 2020
Leap Year

Question 6

Write a program to take two numbers and print if the first number is fully divisible by second number or not.

Solution

x = int(input("Enter first number: "))
y = int(input("Enter second number: "))
print(x % y and "Not Fully Divisible" or "Fully Divisible")

Output

Enter first number: 4
Enter second number: 2
Fully Divisible

Question 7

Write a program to take a 2-digit number and then print the reversed number. That is, if the input given is 25, the program should print 52.

Solution

x = int(input("Enter a two digit number: "))
y = x % 10 * 10 + x // 10
print("Reversed Number:", y)

Output

Enter a two digit number: 25
Reversed Number: 52

Question 8

Try writing program (similar to previous one) for three digit number i.e., if you input 123, the program should print 321.

Solution

x = int(input("Enter a three digit number: "))

d1 = x % 10
x //= 10
d2 = x % 10
x //= 10
d3 = x % 10
y = d1 * 100 + d2 * 10 + d3

print("Reversed Number:", y)

Output

Enter a three digit number: 123
Reversed Number: 321

Question 9

Write a program to take two inputs for day, month and then calculate which day of the year, the given date is. For simplicity, take 30 days for all months. For example, if you give input as: Day3, Month2 then it should print "Day of the year : 33".

Solution

d = int(input("Enter day: "))
m = int(input("Enter month: "))

n = (m - 1) * 30 + d

print("Day of the year:", n)

Output

Enter day: 3
Enter month: 2
Day of the year: 33

Question 10

Write a program that asks a user for a number of years, and then prints out the number of days, hours, minutes, and seconds in that number of years.

How many years? 10
10.0 years is:
3650.0 days
87600.0 hours
5256000.0 minutes
315360000.0 seconds

Solution

y = float(input("How many years? "))

d = y * 365
h = d * 24
m = h * 60
s = m * 60

print(y, "years is:")
print(d, "days")
print(h, "hours")
print(m, "minutes")
print(s, "seconds")

Output

How many years? 10
10.0 years is:
3650.0 days
87600.0 hours
5256000.0 minutes
315360000.0 seconds

Question 11

Write a program that inputs an age and print age after 10 years as shown below:

What is your age? 17
In ten years, you will be 27 years old!

Solution

a = int(input("What is your age? "))
print("In ten years, you will be", a + 10, "years old!")

Output

What is your age? 17
In ten years, you will be 27 years old!

Question 12

Write a program whose three sample runs are shown below:

Sample Run 1:
Random number between 0 and 5 (A) : 2
Random number between 0 and 5 (B) :5.
A to the power B = 32

Sample Run 2:
Random number between 0 and 5 (A) : 4
Random number between 0 and 5 (B) :3.
A to the power B = 64

Sample Run 3:
Random number between 0 and 5 (A) : 1
Random number between 0 and 5 (B) :1.
A to the power B = 1

Solution

import random

a = random.randint(0, 5)
b = random.randint(0, 5)
c = a ** b

print("Random number between 0 and 5 (A) :", a)
print("Random number between 0 and 5 (B) :", b)
print("A to the power B =", c)

Output

Random number between 0 and 5 (A) : 5
Random number between 0 and 5 (B) : 3
A to the power B = 125

Question 13

Write a program that generates six random numbers in a sequence created with (start, stop, step). Then print the mean, median and mode of the generated numbers.

Solution

import random
import statistics

start = int(input("Enter start: "))
stop = int(input("Enter stop: "))
step = int(input("Enter step: "))

a = random.randrange(start, stop, step)
b = random.randrange(start, stop, step)
c = random.randrange(start, stop, step)
d = random.randrange(start, stop, step)
e = random.randrange(start, stop, step)
f = random.randrange(start, stop, step)

print("Generated Numbers:")
print(a, b, c, d, e, f)

seq = (a, b, c, d, e, f)

mean = statistics.mean(seq)
median = statistics.median(seq)
mode = statistics.mode(seq)

print("Mean =", mean)
print("Median =", median)
print("Mode =", mode)

Output

Enter start: 100
Enter stop: 500
Enter step: 5
Generated Numbers:
235 255 320 475 170 325
Mean = 296.6666666666667
Median = 287.5
Mode = 235

Question 14

Write a program to generate 3 random integers between 100 and 999 which is divisible by 5.

Solution

import random

a = random.randrange(100, 999, 5)
b = random.randrange(100, 999, 5)
c = random.randrange(100, 999, 5)

print("Generated Numbers:", a, b, c)

Output

Generated Numbers: 885 825 355

Question 15

Write a program to generate 6 digit random secure OTP between 100000 to 999999.

Solution

import random

otp = random.randint(100000, 999999);

print("OTP:", otp);

Output

OTP: 553072

Question 16

Write a program to generate 6 random numbers and then print their mean, median and mode.

Solution

import random
import statistics

a = random.random()
b = random.random()
c = random.random()
d = random.random()
e = random.random()
f = random.random()

print("Generated Numbers:")
print(a, b, c, d, e, f)

seq = (a, b, c, d, e, f)

mean = statistics.mean(seq)
median = statistics.median(seq)
mode = statistics.mode(seq)

print("Mean =", mean)
print("Median =", median)
print("Mode =", mode)

Output

Generated Numbers:
0.47950245404109626 0.6908539320958872 0.12445888663826654 0.13613724999684718 0.37709141355821396 0.6369609321575742
Mean = 0.40750081141464756
Median = 0.4282969337996551
Mode = 0.47950245404109626

Question 17

Write a program to find a side of a right angled triangle whose two sides and an angle is given.

Solution

import math

a = float(input("Enter base: "))
b = float(input("Enter height: "))
x = float(input("Enter angle: "))

c = math.sqrt(a ** 2 + b ** 2)

print("Hypotenuse =", c)

Output

Enter base: 10.5
Enter height: 5.5
Enter angle: 60
Hypotenuse = 11.853269591129697

Question 18

Write a program to calculate the radius of a sphere whose area (4πr²) is given.

Solution

import math

area = float(input("Enter area of sphere: "))

r = math.sqrt(area / (4 * math.pi))

print("Radius of sphere =", r)

Output

Enter area of sphere: 380.14
Radius of sphere = 5.50005273006328

Question 19

Write a program that inputs a string and then prints it equal to number of times its length, e.g.,

Enter string : "eka"
Result ekaekaeka

Solution

str = input("Enter string: ")
len = len(str)
opStr = str * len
print("Result", opStr)

Output

Enter string: eka
Result ekaekaeka

Question 20

Find the volume of the cylinder (πr²h) as shown:

Radius = 8 cm
Height = 15 cm

Solution

import math

r = 8
h = 15
v = math.pi * r * r * h

print("Volume of Cylinder =", v)

Output

Volume of Cylinder = 3015.928947446201

Question 21

Write a program to calculate the area of an equilateral triangle. (area = (√3 / 4) * side * side).

Solution

import math

side = float(input("Enter side: "))
area = math.sqrt(3) / 4 * side * side

print("Area of triangle =", area)

Output

Enter side: 5
Area of triangle = 10.825317547305481

Question 22

Write a program to input the radius of a sphere and calculate its volume (V = 4/3πr³)

Solution

import math

r = float(input("Enter radius of sphere: "))
v = 4 / 3 * math.pi * r ** 3

print("Volume of sphere = ", v)

Output

Enter radius of sphere: 3.5
Volume of sphere =  179.59438003021648

Question 23

Write a program to calculate amount payable after simple interest.

Solution

p = float(input("Enter principal: "))
r = float(input("Enter rate: "))
t = float(input("Enter time: "))

si = p * r * t / 100
amt = p + si

print("Amount Payable =", amt)

Output

Enter principal: 55000.75
Enter rate: 14.5
Enter time: 3
Amount Payable = 78926.07625

Question 24

Write a program to calculate amount payable after compound interest.

Solution

p = float(input("Enter principal: "))
r = float(input("Enter rate: "))
t = float(input("Enter time: "))

amt = p * (1 + r / 100) ** t

print("Amount Payable =", amt)

Output

Enter principal: 15217.75
Enter rate: 9.2
Enter time: 3
Amount Payable = 19816.107987312007

Question 25

Write a program to compute (a + b)³ using the formula a³ + b³ + 3a²b + 3ab²

Solution

a = int(input("Enter a: "))
b = int(input("Enter b: "))
res = a ** 3 + b ** 3 + 3 * a ** 2 * b + 3 * a * b ** 2

print("Result =", res)

Output

Enter a: 3
Enter b: 5
Result = 512