PCEP Control Flow, Loops, Lists and Logic Practice Test 3 — 15 Questions

Question 1

A developer needs to implement a loop that prints numbers from 10 down to 1. Which loop correctly achieves this?

Accepted Answer

for i in range(10, 0, -1): print(i). `range(10, 0, -1)` generates numbers from 10 down to 1 inclusive. The start is 10, the stop is 0 (exclusive), and the step is -1, so the sequence is 10, 9, 8, ..., 1. This matches the requirement exactly.

Answer

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

Answer

for i in reversed(range(1, 10)): print(i)

Answer

for i in range(10, 1, -1): print(i)

Question 2

A program contains a nested while loop. The inner loop should run as long as a condition is True, but the outer loop should stop after 3 iterations. Which code structure is correct? (Assume the inner loop condition is inner < 5.)

Accepted Answer

outer = 0
while outer < 3:
    inner = 0
    while inner < 5:
        # do something
        inner += 1
    outer += 1. Ly implements a nested while loop where the inner loop runs while `inner < 5` and the outer loop runs while `outer < 3`. The inner loop increments `inner` to control its own termination, and the outer loop increments `outer` after the inner loop completes, ensuring exactly 3 iterations of the outer loop. This matches the requirement that the outer loop stops after 3 iterations while the inner loop runs as long as its condition is True.

Answer

for outer in range(3):
    inner = 0
    while inner < 5:
        # do something
        inner += 1

Answer

outer = 0
while outer < 3:
    for inner in range(5):
        # do something
        outer += 1

Answer

outer = 0
while outer < 3:
    inner = 0
    while inner < 5:
        # do something
        outer += 1
        inner += 1

Question 3

Which two of the following list methods modify the original list in place? (Choose two.)

Accepted Answer

sort(). A is correct because the `sort()` method sorts the list in place, meaning it modifies the original list object without creating a new one. D is correct because `append()` adds an element to the end of the list, directly mutating the original list.

Answer

count()

Answer

sorted()

Answer

copy()

Question 4

Which three of the following statements about lists are true? (Choose three.)

Accepted Answer

Lists can be indexed with integers.. Lists in Python are ordered sequences that support indexing with integers, starting from 0 for the first element and negative integers for reverse indexing. This allows direct access to any element by its position, a fundamental feature of sequence types in Python.

Answer

Lists have a fixed size once created.

Answer

Lists can only contain elements of the same data type.

Question 5

Refer to the exhibit. What is the output?

Accepted Answer

1. (1). The code initializes x to 0, then iterates over the list [1, 2, 3, 4, 5]. In each iteration, it first assigns the current number to x, then checks if the number equals 1. On the first iteration, i is 1, so x becomes 1, then the condition i == 1 is true, causing the loop to break. The print(x) statement after the loop outputs the final value of x, which is 1.

Answer

5

Answer

2

Answer

9

Question 6

What is the output of the following code?

numbers = [1, 2, 3, 4, 5]
total = 0
for i in numbers:
    if i % 2 == 0:
        continue
    total += i
print(total)

Accepted Answer

9. The exhibit shows code that iterates over the list [1, 2, 3, 4, 5] and uses `if i % 2 == 0: continue` to skip even numbers. Only odd numbers (1, 3, 5) are summed, giving 1 + 3 + 5 = 9. Therefore, option D is correct.

Answer

10

Answer

8

Answer

6

Question 7

What is the output of the following code?

for i in range(1, 6):
    if i == 3:
        continue
    print(i, end=' ')

Accepted Answer

1 2 4 5. The code uses a for loop with range(1, 6) and a continue statement when i == 3. When i equals 3, the continue skips the print(i, end=' ') statement, so 3 is not printed. The loop iterates through 1, 2, 4, and 5, producing the output '1 2 4 5'.

Answer

1 2 3 4 5

Answer

1 2 4

Answer

1 2 3 4

Question 8

A company maintains a list of employee names. They want to check if 'Alice' is in the list. Which of the following is the most Pythonic way to achieve this?

Accepted Answer

if 'Alice' in employees:. The most Pythonic way because it uses the `in` operator, which directly checks membership in a list with a single, readable expression. This approach is idiomatic Python, leveraging the language's built-in support for membership testing without manual iteration or exception handling.

Answer

employees.contains('Alice')

Answer

for name in employees: if name == 'Alice': found = True; break

Answer

if employees.index('Alice') != -1:

Question 9

A developer writes a while loop to count down from 10 to 1 and then stop. Which condition should be used?

Accepted Answer

while counter > 0:. The while loop must continue as long as the counter is greater than 0, counting down from 10 to 1. When counter becomes 0, the condition `counter > 0` evaluates to False, and the loop terminates, stopping exactly at 1.

Answer

while counter != 0:

Answer

while counter >= 0:

Answer

while counter < 10:

Question 10

A team is reviewing code that uses if-elif-else to classify a test score. They notice that for score 90, it prints 'B' instead of 'A'. Which of the following best explains the issue?

Accepted Answer

The condition for 'A' should be checked before 'B'. In an if-elif-else chain, the first matching condition is executed and the rest are skipped. If the condition for 'A' (e.g., score >= 90) is placed after the condition for 'B' (e.g., score >= 80), a score of 90 will match the 'B' condition first and never reach the 'A' condition. To fix this, the most restrictive condition (highest grade) must be checked first.

Answer

The order of conditions does not matter

Answer

The elif condition should use >= instead of >

Answer

The code uses elif instead of else if

Question 11

A developer needs to write a loop that prints all even numbers from a list. They attempt: for num in numbers: if num % 2 == 0: print(num). However, they want a more efficient approach using list comprehension. Which alternative achieves the same result?

Accepted Answer

for even in [num for num in numbers if num % 2 == 0]: print(even). It uses a list comprehension to generate a list of even numbers, then iterates over that list with a for loop, printing each even number. This achieves the same result as the original loop but with the efficiency of list comprehension for filtering, while still printing each number individually.

Answer

print([num for num in numbers if num % 2 == 0])

Answer

for num in numbers: print(num if num % 2 == 0 else None)

Answer

print([num % 2 == 0 for num in numbers])

Question 12

A company uses a for loop to iterate over a list of transaction amounts. They want to skip negative amounts. Which statement inside the loop correctly achieves this?

Accepted Answer

if amount < 0: continue. The `continue` statement immediately jumps to the next iteration of the loop, skipping any remaining code in the current iteration. When `amount < 0`, the loop will not process that negative transaction and will move to the next element in the list, effectively skipping negative amounts.

Answer

if amount < 0: amounts.remove(amount)

Answer

if amount < 0: break

Answer

if amount < 0: pass

Question 13

A developer writes: result = [x**2 for x in range(10) if x % 2 == 0]. What does this code produce?

Accepted Answer

A list containing [0, 4, 16, 36, 64]. The code uses a list comprehension with a conditional filter: `[x**2 for x in range(10) if x % 2 == 0]`. It iterates over numbers 0 through 9, keeps only even numbers (those where `x % 2 == 0`), squares each, and collects the results into a list. The resulting list is `[0, 4, 16, 36, 64]`, which are the squares of the even numbers 0, 2, 4, 6, and 8.

Answer

A list of even numbers squared

Answer

A generator object

Answer

A list of squares of all numbers from 0 to 9

Question 14

A team observes that the following code prints 'Found' even when the item is not in the list. Code: for item in mylist: if item == target: print('Found'); break; else: print('Not found'). Which modification ensures it correctly prints 'Not found' only if the item is not present?

Accepted Answer

Align the else with the for statement (for-else construct). The original code uses a for-else construct where the else block executes after the loop completes normally (i.e., without a break). However, the code has a syntax error: the else is incorrectly indented as part of the if statement, causing it to execute on every iteration when the condition is false. Aligning the else with the for statement (for-else construct) ensures the else block runs only if the loop finishes without hitting a break, which occurs when the item is not found.

Answer

Move else inside the if block

Answer

Replace break with continue

Answer

Use a flag variable to track found status

Question 15

A developer writes a recursive function to compute factorial, but it causes a RecursionError. Which of the following is the most likely cause?

Accepted Answer

The function lacks a base case to stop recursion. A recursive function must have a base case that stops further recursive calls. Without it, the function calls itself indefinitely until the recursion limit is exceeded, raising a RecursionError. In Python, the default recursion limit is 1000, and exceeding it triggers this error.

Answer

The function returns a string instead of an integer

Answer

The function modifies a global variable incorrectly

Answer

The function uses too many parameters