Q: A bank account starts with $\$100$ and earns $5\%$ interest per year. The target balance is $\$1000$. Which while loop condition correctly models the process of accumulating interest until the target is reached?

$\text{while balance < TARGET:}$

Q: What is a common cause of infinite loops in Python when using a while loop?

Forgetting to update the test variable inside the loop.

Q: A program asks the user to enter numbers until -1 is entered, then calculates the average. What is the role of -1 in this program?

It is a sentinel value that signals the end of input.

Q: Which statement about indentation in Python is correct?

All statements in the body of a loop must be indented to the same column position.

Q: Which of the following best describes an event-controlled loop?

A loop that continues until a specific event occurs.

Q: What is the main difference between a decision structure and a repetition structure in Python?

A decision structure chooses between two or more paths based on a condition, while a repetition structure executes code repeatedly as long as a condition is true.

Q: Which of the following is a common off-by-one error in count-controlled loops?

Using $\text{while counter < 5}$ when you want to count 5 items starting from 0.

Q: A program is designed to find the maximum value entered by the user. What is a necessary step to avoid errors if the user enters no values?

Check if the first input is empty before converting to float.

Q: Which of the following scenarios is best handled by a while loop with input validation?

Prompting the user until they enter a valid menu choice.

Question 1

Which of the following best describes a repetition structure in Python programming?

Accepted Answer

A structure that executes a block of code repeatedly as long as a condition is true.

Question 2

Given the following code snippet, what is the output?

$	ext{counter = 1}$
$	ext{while counter <= 3:}$
$\quad 	ext{print(counter)}$
$\quad 	ext{counter = counter + 1}$

Accepted Answer

1 2 3

Question 3

A bank account starts with $\$100$ and earns $5\%$ interest per year. The target balance is $\$1000$. Which while loop condition correctly models the process of accumulating interest until the target is reached?

Accepted Answer

$	ext{while balance < TARGET:}$

Question 4

What is a common cause of infinite loops in Python when using a while loop?

Accepted Answer

Forgetting to update the test variable inside the loop.

Question 5

Which of the following is an example of a count-controlled loop?

Accepted Answer

$	ext{while counter <= 10:}$

Question 6

A program asks the user to enter numbers until -1 is entered, then calculates the average. What is the role of -1 in this program?

Accepted Answer

It is a sentinel value that signals the end of input.

Question 7

Consider the following code:

$	ext{finger = 1}$
$	ext{while finger <= 5:}$
$\quad 	ext{print(finger)}$
$\quad 	ext{finger = finger + 1}$

How many times will the loop execute?

Accepted Answer

5

Question 8

Which statement about indentation in Python is correct?

Accepted Answer

All statements in the body of a loop must be indented to the same column position.

Question 9

What is the output of the following code if the user enters 3, 4, 5, and then -1?

$	ext{sum1 = 0}$
$	ext{i = 0}$
$	ext{number = eval(input('Enter a number: '))}$
$	ext{while number != -1:}$
$\quad i += 1$
$\quad sum1 += number$
$\quad number = eval(input('Enter a number: '))$
$	ext{print('The average is {0:.2f}'.format(sum1/i))}$

Accepted Answer

The average is 4.00

Question 10

Which of the following best describes an event-controlled loop?

Accepted Answer

A loop that continues until a specific event occurs.

Question 11

What is the main difference between a decision structure and a repetition structure in Python?

Accepted Answer

A decision structure chooses between two or more paths based on a condition, while a repetition structure executes code repeatedly as long as a condition is true.

Question 12

Which of the following is a common off-by-one error in count-controlled loops?

Accepted Answer

Using $	ext{while counter < 5}$ when you want to count 5 items starting from 0.

Question 13

Which Python statement immediately terminates a loop when executed?

Accepted Answer

break

Question 14

A program is designed to find the maximum value entered by the user. What is a necessary step to avoid errors if the user enters no values?

Accepted Answer

Check if the first input is empty before converting to float.

Question 15

Which of the following scenarios is best handled by a while loop with input validation?

Accepted Answer

Prompting the user until they enter a valid menu choice.

Question 16

What is the effect of the continue statement in a while loop?

Accepted Answer

It skips the rest of the current iteration and returns to the loop header.

Question 17

Which of the following is a correct way to count the number of negative values entered by a user until they press Enter?

Accepted Answer

$	ext{while number != '':}$
ewline\quad 	ext{if value < 0:}$
ewline\quad\quad 	ext{negatives += 1}$

Question 18

A program compares adjacent values entered by the user and prints 'Duplicate input' if two consecutive values are the same. What is a necessary step to avoid errors if the user enters nothing?

Accepted Answer

Print 'No values entered.' if the first input is empty.

Question 19

Which of the following menu-driven programs is best implemented using a while loop?

Accepted Answer

A program that asks the user to select options until they choose to quit.

Control Structures and the while Loop in Python

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