Quiz: Repetition: Loops and Iteration

Test your understanding before moving on. Target: 70% or higher to proceed confidently.

Section 1: Multiple Choice (1 point each)

1. What values does range(3, 8) produce?

• A) 3, 4, 5, 6, 7, 8
• B) 3, 4, 5, 6, 7
• C) 4, 5, 6, 7
• D) 3, 4, 5, 6, 7, 8, 9

2. How many times does the body of this loop execute?

for i in range(0, 10, 3):
    print(i)

• A) 3
• B) 4
• C) 10
• D) 0

3. Which loop is best suited for asking the user to re-enter input until it's valid?

• A) for loop with range()
• B) while loop
• C) Nested for loop
• D) Either for or while — there's no difference

4. What is the output of this code?

total = 0
for num in range(1, 5):
    total += num
print(total)

• A) 15
• B) 10
• C) 4
• D) 5

5. What does the break statement do?

• A) Skips to the next iteration of the loop
• B) Ends the program entirely
• C) Immediately exits the enclosing loop
• D) Pauses the loop for one second

6. What is the output of this code?

for i in range(5):
    if i == 3:
        continue
    print(i, end=" ")

• A) 0 1 2
• B) 0 1 2 4
• C) 0 1 2 3 4
• D) 3

7. In a nested loop where the outer loop runs 3 times and the inner loop runs 5 times, how many times does the inner loop's body execute?

• A) 3
• B) 5
• C) 8
• D) 15

8. Which of the following correctly describes the accumulator pattern?

• A) Initialize a variable inside the loop, update it outside the loop, use it during the loop
• B) Initialize a variable before the loop, update it inside the loop, use it after the loop
• C) Use break to accumulate values in a list
• D) Use range() to automatically sum a sequence

9. What is an infinite loop?

• A) A loop that runs exactly once
• B) A loop that iterates over an infinitely long list
• C) A loop whose exit condition is never met, so it runs forever
• D) A loop with more than 1,000 iterations

10. What is the output of this code?

for i in range(3):
    for j in range(2):
        print(f"{i}-{j}", end=" ")
    print()

• A) 0-0 0-1 on the first line, 1-0 1-1 on the second, 2-0 2-1 on the third
• B) 0-0 1-0 2-0 on the first line, 0-1 1-1 2-1 on the second
• C) 0-0 0-1 0-2 1-0 1-1 1-2 all on one line
• D) 0-0 1-1 2-2 all on one line

Section 2: True/False with Justification (1 point each)

11. "range(5) produces the values 1, 2, 3, 4, 5."

12. "A while loop always executes its body at least once."

13. "The else clause of a loop runs only when the loop exits due to a break statement."

14. "The accumulator pattern requires the accumulator to be initialized to 0."

Section 3: Short Answer (2 points each)

15. Explain in 2-3 sentences why an infinite loop is usually a bug, and describe how to identify one when your program is running.

16. Write the range() call that produces each sequence of values. Don't use any code besides range().

a) 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 b) 5, 6, 7, 8, 9, 10 c) 10, 8, 6, 4, 2 d) 100, 200, 300, 400, 500

17. A student writes this code to compute the average of 5 numbers entered by the user. Identify the bug and explain how to fix it.

for i in range(5):
    num = float(input("Enter a number: "))
    total = 0
    total += num
average = total / 5
print(f"Average: {average}")

total = 0
for i in range(5):
    num = float(input("Enter a number: "))
    total += num
average = total / 5
print(f"Average: {average}")

Section 4: Code Tracing (2 points each)

18. Trace through this code and write the exact output.

result = 1
for i in range(1, 5):
    result *= i
    print(f"i={i}, result={result}")

i=1, result=1
i=2, result=2
i=3, result=6
i=4, result=24

19. Trace through this code and write the exact output.

x = 16
count = 0
while x > 1:
    x = x // 2
    count += 1
print(f"x={x}, count={count}")

x=1, count=4

20. Trace through this code and write the exact output.

for i in range(4):
    if i == 2:
        break
    print(i, end=" ")
else:
    print("done")
print("after")

0 1 after

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