Selections

Question 1

A Boolean expression is an expression that evaluates to a ______ value _____ or ______.

Answer 1

A Boolean expression is an expression that evaluates to a Boolean value True or False.

Question 2

The word True is \_\_\_\_\_\_\_\_.
 A. a Python keyword
 B. a Boolean literal
 C. same as value 1
 D. same as value 0

Answer 2

A. a Python keyword

B. a Boolean literal

Question 3

What does the randint(a, b) function do?

Answer 3

The randint(a, b) function can be used to generate a random integer between a and b, inclusively.

Question 4

How do you generate a random integer i such that 0 <= i < 20?

Answer 4

random.randrange(0, 20) or random.randint(0, 19)

Question 5

How do you generate a random integer i such that 10 <= i < 20?

Answer 5

random.randrange(10, 20) or random.randint(10, 19)

Question 6

How do you generate a random integer i such that 10 <= i <= 50?

Answer 6

random.randrange(10, 50 + 1) or random.randint(10, 50)

Question 7

How do you generate a random integer 0 or 1?

Answer 7

random.randrange(0, 2) or random.randint(0, 1)

Question 8

To generate a random integer between 0 and 5, use \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
 A. random.randint(0, 5)
 B. random.randint(0, 6)
 C. random.randrange(0, 5)
 D. random.randrange(0, 6)

Answer 8

A. random.randint(0, 5)
D. random.randrange(0, 6)

Hint: In A, randint(0, 5) returns a sequence from 0, 1, 2, 3, 4, 5. In B, randint(0, 6) returns a sequence from 0, 1, 2, 3, 4, 5, 6. In C, randrange(0, 5) returns a sequence from 0, 1, 2, 3, 4. In D, randrange(0, 6) returns a sequence from 0, 1, 2, 3, 4, 5. A and D are correct.

Question 9

random.random() returns ____________.
A. a float number i such that 0 < i < 1.0
B. a float number i such that 0 <= i < 1.0
C. a float number i such that 0 <= i <= 1.0
D. a float number i such that 0 < i < 2.0

Answer 9

B. a float number i such that 0 <= i < 1.0

Question 10

Suppose isPrime is a boolean variable, which of the following is the correct and best statement for testing if isPrime is true.
 A. if isPrime = True:
 B. if isPrime == True:
 C. if isPrime:
 D. if not isPrime = False:
 E. if not isPrime == False:

Answer 10

B. if isPrime == True:
C. if isPrime:

Both correct, but C is better.

Question 11

Write an if statement that increases pay by 3% if score is greater than 90, otherwise it increases pay by 1%.

Answer 11

if score > 90:
pay *= 1.03
else:
pay *= 1.01

Question 12

What is the outpout of the code in (a) and (b) if number is 30 and 35?
(a)
if number % 2 == 0:
print(number, “is even.”)

print(number, "is odd.")
(b)
if number % 2 == 0: 
    print(number, "is even.")
else: 
    print(number, "is odd.")

Answer 12

If number is 30,
(a) displays
30 is even
30 is odd

(b) displays
30 is even

If number is 35,
(a) displays
35 is odd

(b) displays
35 is odd

Question 13

Are the following statements correct? Which one is better?
(a)
if age < 16:
print(“Cannot get a driver’s license”)
if age >= 16:
print(“Can get a driver’s license”)

(b)            
if age < 16:
    print("Cannot get a driver's license") 
else: 
    print("Can get a driver's license")

Answer 13

Both are correct. (b) is better. Both conditions in (a) are tested. In (b) the condition is tested only once.

Question 14

Rewrite the following statement using a Boolean expression:
if count % 10 == 0:
    newLine = True
else:
    newLine = False

Answer 14

newLine = (count % 10 == 0)

Question 15

Analyze the following code:

even = False
if even = True:
print(“It is even!”)
A. The program has a syntax error in line 1 (even = False)
B. The program has a syntax error in line 2 if even = True is not a correct condition. It should be replaced by if even == True: or simply better using if even:.
C. The program runs, but displays nothing.
D. The program runs and displays It is even!.

Answer 15

B. The program has a syntax error in line 2 if even = True is not a correct condition. It should be replaced by if even == True: or simply better using if even:.

Question 16

Analyze the following code.

even = False
if even:
print(“It is even!”)
A. The code displays It is even!
B. The code displays nothing.
C. The code is wrong. You should replace if even: with if even == True:
D. The code is wrong. You should replace if even: with if even = True:

Answer 16

B. The code displays nothing.

Hint: even is False. Nothing is displayed.

Question 17

Analyze the following code:

Code 1:

if number % 2 == 0:
even = True
else:
even = False

Code 2:

even = number % 2 == 0
A. Code 1 has compile errors.
B. Code 2 has compile errors.
C. Both Code 1 and Code 2 have compile errors.
D. Both Code 1 and Code 2 are correct, but Code 2 is better.

Answer 17

D. Both Code 1 and Code 2 are correct, but Code 2 is better.

Question 18

Suppose income is 4001, what will be displayed by the following code?

if income > 3000:
    print("Income is greater than 3000")
elif income > 4000:
    print("Income is greater than 4000")
 A. none
 B. Income is greater than 3000
 C. Income is greater than 3000 followed by Income is greater than 4000
 D. Income is greater than 4000
 E. Income is greater than 4000 followed by Income is greater than 3000

Answer 18

B. Income is greater than 3000

Hint: Since income is 4001, the condition (income > 3000) is true. So statement for the true case is executed. The elif clause is not executed in this case.

Question 19

The __________ function immediately terminates the program.

Answer 19

sys.exit()

Question 20

Assuming that x is 1, show the result of the following Boolean expressions.
True and (3 > 4)
not (x > 0) and (x > 0)
    (x > 0) or (x < 0)
    (x != 0) or (x == 0)
    (x >= 0) or (x < 0)
    (x != 1) == not (x == 1)

Answer 20

(true) and (3 > 4)
False

not(x > 0) and (x > 0)
False

(x > 0) or (x < 0)
True

(x != 0) or (x == 0)
True

(x >= 0) or (x < 0)
True

(x != 1) == not (x == 1)
True

Question 21

(a) Write a Boolean expression that evaluates to True if variable num is between 1 and 100. (b) Write a Boolean expression that evaluates to True if variable num is between 1 and 100 or the number is negative.

Answer 21

(a) (x > 1) and (x < 100)

b) (x > 1 and x < 100) or (x < 0

Question 22

(a) Write a Boolean expression for |x - 5| < 4.5. (b) Write a Boolean expression for |x - 5| > 4.5.

Answer 22

(a) (-4.5 <= x - 5 < 4.5)

b) (x - 5 > 4.5 and x - 5 <= -4.5

Question 23

Assuming x = 4 and y = 5, show the result of the following Boolean expressions.
x >= y >= 0
x <= y >= 0
x != y == 5
(x != 0) or (x == 0)

Answer 23

x >= y >= 0 False
x <= y >= 0 True
x != y == 5 True
(x != 0) or (x == 0) True

Question 24

Are the following expressions equivalent?

a. (x >= 1) and (x < 10)
b. (1 <= x < 10)

Answer 24

Yes

Question 25

What is the value of the expression 50 <= x <= 100 if x is 45, 67, or 101?

Answer 25

It is False for x is 45.
It is True for x is 67.
It is False for x is 101.

Question 26

Write a Boolean expression that evaluates to true if weight is greater than 50 and height is greater than 160.

Answer 26

weight > 50 and height > 160.

Question 27

Write a Boolean expression that evaluates to true if either weight is greater than 50 or height is greater than 160, but not both.

Answer 27

(weight > 50 or height > 160) and not (weight > 50 and height > 160)

Question 28

Which of the Boolean expressions below is incorrect?
 A. True and 3 => 4
 B. !(x > 0) and (x > 0)
 C. (x > 0) or (x < 0)
 D. (x != 0) or (x = 0)
 E. (-10 < x < 0)

Answer 28

A. True and 3 => 4
B. !(x > 0) and (x > 0)
D. (x != 0) or (x = 0)

Hint: a: (3 => 4) should be (3 >= 4), b: !(x > 0) should be not (x > 0) d: (x = 0) should be (x == 0)

Question 29

Which of the following is the correct expression that evaluates to True if the number x is between 1 and 100 or the number is negative?
 A. 1 < x < 100 and x < 0
 B. (x < 100 and x > 1) or (x < 0)
 C. (x < 100 and x > 1) and (x < 0)
 D. (1 > x > 100) or (x < 0)

Answer 29

The correct answer is ABCD.

They are all correct.

Question 30

To check whether a char variable ch is an uppercase letter, you write \_\_\_\_\_\_\_\_\_\_\_.
 A. (ch >= 'A' and ch >= 'Z')
 B. (ch >= 'A' and ch <= 'Z')
 C. (ch >= 'A' or ch <= 'Z')
 D. ('A' <= ch <= 'Z')

Answer 30

B. (ch >= ‘A’ and ch <= ‘Z’)
D. (‘A’ <= ch <= ‘Z’)

B and D are correct.

Question 31

Given |x| <= 4, Which of the following is true?
 A. x <= 4 and x >= 4
 B. x <= 4 and x > -4
 C. x <= 4 and x >= -4
 D. x <= 4 or x >= -4

Answer 31

C. x <= 4 and x >= -4

The correct answer is C.

Hint: |x| <= 4 means -4 <= x <= 4. That is x <= 4 and x >= -4. |x| <= 4 is true for x being -4, -3, 0, 2, 4, etc. So the correct answer is C.

Question 32

Given |x| >= 4, Which of the following is true?
 A. x >= 4 and x <= -4
 B. x >= 4 or x <= -4
 C. x >= 4 and x < -4
 D. x >= 4 or x <= -4

Answer 32

B. x >= 4 or x <= -4

The correct answer is B.

Hint: |x| >= 4 means x >= 4 or x <= -4. |x| >= 4 is true for x being -4, -5, -6, 4, 5, 6, etc. So B is correct.

Question 33

Assume x = 14 and y = 15, Which of the following is true?
 A. x % 2 == 0 and y % 2 == 0
 B. x % 2 == 0 and y % 2 == 1
 C. x % 2 == 0 or y % 2 == 0
 D. x % 2 != 0 and y % 2 != 0

Answer 33

The correct answer is BC.

Question 34

Which of the following is equivalent to x != y?
 A. not (x == y)
 B. x > y and x < y
 C. x > y or x < y
 D. x >= y or x <= y

Answer 34

The correct answer is AC.

Question 35

What will be displayed by the following code?

ch = ‘F’
if ch >= ‘A’ and ch <= ‘Z’:
print(ch)

A. F
B. f
C. nothing
D. F f

Answer 35

A. F

Question 36

What happens if you enter an integer as 05?

Answer 36

It will be the same as entering 5.

Question 37

Rewrite the following if statements using a conditional expression.
(a)            
if ages >= 16:
    ticketPrice = 20
else:
    ticketPrice = 10

(b)
if count % 10 == 0:
    print(count, end = "*")
else:
    print(count, end = "#")

Answer 37

(a) ticketPrice = 20 if (ages >= 16) else 10

b) print(count, end = “*” if count % 10 == 0 else “#”

Question 38

Rewrite the following conditional expressions using if/else statements.

a. score = 3 * scale if x > 10 else 4 * scale
b. tax = income * 0.2 if income > 10000 else income * 0.17 + 1000
c. print(i if number % 3 == 0 else j)

Answer 38

A:
if x > 10:
    score = 3 * scale
else: 
    score = 4 * scale

B:
if income > 10000:
    tax = income * 0.2
else: 
    tax = income * 0.17 + 1000

C:
if number % 3 == 0:
    print(i)
else: 
    print(j)

Question 39

Rewrite conditional expression that returns -1 or 1 randomly.

Answer 39

-1 if random.randint(0, 1) == 0 else 1

Question 40

What is tax if income is 1000 and 20000, respectively?

a. tax = income * 0.2 if income > 10000 else 0.1
b. tax = income * (0.2 if income > 10000 else 0.1)

Answer 40

For income 1000, a. 0.1 and b. 100.0

For income 20000, a. 4000.0 and b. 4000.0

Question 41

Analyze the following code fragments that assign a boolean value to the variable even.

Code 1: 
if number % 2 == 0:
    even = True
else: 
    even = False

Code 2:
even = True if number % 2 == 0 else False

Code 3:
even = number % 2 == 0

A. Code 2 has a syntax error, because you cannot have True and False literals in the conditional expression.
B. Code 3 has a syntax error, because you attempt to assign number to even.
C. All three are correct, but Code 1 is preferred.
D. All three are correct, but Code 2 is preferred.
E. All three are correct, but Code 3 is preferred.

Answer 41

E. All three are correct, but Code 3 is preferred.

Question 42

The order of the precedence (from high to low) of the operators +, *, and, or is:
 A. and, or, *, +
 B. *, +, and, or
 C. *, +, and, or
 D. *, +, or, and
 E. or, and, *, +

Answer 42

C. *, +, and, or

The correct answer is C.

Question 43

Which of the following operators are right-associative.
 A. *
 B. +
 C. %
 D. and
 E. =

Answer 43

E. =

Question 44

Which of the following statements are True?
A. (x > 0 and x < 10) is same as (x > 0 and x < 10)
B. (x > 0 or x < 10) is same as (0 < x < 10)
C. (x > 0 or x < 10 and y < 0) is same as (x > 0 or (x < 10 and y < 0))
D. (x > 0 or x < 10 and y < 0) is same as ((x > 0 or x < 10) and y < 0)

Answer 44

The correct answer is AC.

Question 45

A Boolean type variable can store a ____ or _____ value

Answer 45

True or False