PCEP Practice Test 31 — 15 Questions

Question 1

A game developer writes a loop to process a list of player scores: `scores = [45, 82, 67, 91]`. She wants to print only the scores that are greater than 80. Which loop correctly accomplishes this?

Accepted Answer

for score in scores:
    if score > 80:
        print(score). To print only scores greater than 80, the loop must iterate over all scores and use an `if` statement with the `>` operator to print those that satisfy the condition. The correct snippet does exactly that, printing 82 and 91. Other options use incorrect comparison operators or misplaced print statements.

Answer

for score in scores:
    if score < 80:
        print(score)

Answer

for score in scores:
    if score >= 80:
        print(score)

Answer

for score in scores:
    print(score)
    if score > 80:
        break

Question 2

A Python developer is writing a function that takes a list of numbers and returns a new list containing only the numbers that are divisible by 3 or 5. The developer writes the following code:

def filter_numbers(nums):
    result = []
    for n in nums:
        if n % 3 == 0 or n % 5 == 0:
            result.append(n)
    return result

Which statement about this function is true?

Accepted Answer

The function correctly returns numbers divisible by 3 or 5, and it does not modify the original list.. The function iterates over the input list, checks each number for divisibility by 3 or 5 using the modulo operator and logical OR, and appends qualifying numbers to a new list. It does not modify the original list, and it correctly implements the specified filtering. The other statements are either incorrect or describe behavior that does not occur.

Answer

The function correctly returns numbers divisible by 3 or 5, but it will raise an error if the list contains a zero.

Answer

The function correctly returns numbers divisible by 3 or 5, but it includes duplicates if the input list has duplicates.

Answer

The function correctly returns numbers divisible by 3 or 5, but it uses a logical OR when it should use a logical AND to meet the requirement.

Question 3

A quality-control engineer stores defect codes in a list `codes` and wants to print each code until a sentinel value `'STOP'` is encountered, at which point the loop should end without printing `'STOP'`. Which loop correctly achieves this behavior?

Accepted Answer

for c in codes:
    if c == 'STOP':
        break
    print(c). The correct loop checks each element for the sentinel before any output and uses break to exit the entire loop. Placing the break before the print ensures the sentinel is never displayed, and break ends iteration immediately so no later codes are processed. This matches the engineer's requirement precisely.

Answer

for c in codes:
    if c == 'STOP':
        continue
    print(c)

Answer

for c in codes:
    while c != 'STOP':
        print(c)

Answer

for c in codes:
    print(c)
    if c == 'STOP':
        break

Question 4

During a lab exercise, a student writes the following code to print a countdown from 3 down to 1, but the code enters an infinite loop and never stops. The code is:

count = 3
while count > 0:
    print(count)

Which change makes the loop terminate after printing 3, 2, and 1?

Accepted Answer

Add the statement count = count - 1 inside the loop body.. A while loop repeats as long as its condition stays true, so the counter must move toward the exit value on each pass. Reducing count by one each iteration makes the sequence 3, 2, 1 and then 0, at which point the condition fails and execution continues after the loop. Without such an update the condition never changes.

Answer

Add the statement count = count + 1 inside the loop body.

Answer

Change the condition to while count < 0:

Answer

Add the statement count += 0 inside the loop body.

Question 5

A data analyst has a list named readings containing numeric sensor values. She needs to build a new list that contains only the values strictly greater than 10, preserving their original order. Which code fragment produces this result?

Accepted Answer

filtered = [x for x in readings if x > 10]. A filtering list comprehension keeps only the elements that satisfy the condition and preserves their original order. Writing the element expression as x and placing the comparison after if yields the desired numeric values. Using an inclusive comparison admits boundary values, putting the comparison itself in the expression yields Booleans, and appending a reverse slice destroys the original ordering.

Answer

filtered = [x for x in readings if x >= 10]

Answer

filtered = [x > 10 for x in readings]

Answer

filtered = [x for x in readings if x > 10][::-1]

Question 6

A validation script defines a list named flags containing boolean values. The script must determine whether every flag is True and print 'All clear' only in that case; otherwise it should print 'Check needed'. Which code fragment implements this logic correctly?

Accepted Answer

if all(flags):
    print('All clear')
else:
    print('Check needed'). Determining that every element is True requires a check that inspects all elements and fails if any is falsy. The built-in all function does exactly that, returning True only when every element is truthy and False otherwise, which maps directly onto the two required messages.

Answer

if flags:
    print('All clear')
else:
    print('Check needed')

Answer

if any(flags):
    print('All clear')
else:
    print('Check needed')

Answer

if flags == True:
    print('All clear')
else:
    print('Check needed')

Question 7

A Python programmer is reviewing a script that processes a list of order totals. The script must print each total that is greater than 100 and stop scanning entirely the first time it encounters a total of exactly 0. Which two statements about the loop logic are correct? (Choose two.)

Accepted Answer

A break statement placed inside the loop immediately terminates the loop when the total equals 0.. Stopping a scan at a sentinel value is the classic use case for break, which exits the innermost loop immediately. Pairing it with an if that compares the current total to 0 gives the required early termination. The continue statement only skips to the next iteration, and using exceptions for ordinary control flow is discouraged, so those approaches fail to meet the requirement.

Answer

Wrapping the loop in a try block and raising an exception at zero is the idiomatic way to stop iteration.

Answer

A continue statement placed inside the loop would stop the entire scan when the total equals 0.

Answer

The condition for printing must be checked before the zero check, or zero totals could be printed.

Question 8

A warehouse script stores stock quantities in the list levels = [4, 0, 7, 0, 2]. A developer wants to build a new list, in_stock, containing only the quantities greater than zero, preserving the original order. Which code correctly produces [4, 7, 2]?

Accepted Answer

in_stock = [q for q in levels if q > 0]. A comprehension of the form [expression for item in iterable if condition] walks the list in order and includes only items satisfying the condition. Testing q > 0 excludes the zeros while keeping 4, 7, and 2 in their original positions, and it builds a separate list rather than modifying the source.

Answer

in_stock = [levels[q] for q in levels if q > 0]

Answer

in_stock = [q for q in levels if q >= 0]

Answer

in_stock = [q if q > 0 for q in levels]

Question 9

A developer is writing a Python function that must accept any number of positional arguments and return their sum. The function should also work when called with zero arguments. Which function definition correctly achieves this?

Accepted Answer

def total(*nums): return sum(nums). The function must handle any number of positional arguments, including zero. Using *nums in the function definition collects arguments into a tuple, and sum() correctly adds them, returning 0 for an empty tuple. Other options either restrict the number of arguments or incorrectly unpack the tuple.

Answer

def total(nums): return sum(nums)

Answer

def total(nums=0): return sum(nums)

Answer

def total(*nums): return sum(*nums)

Question 10

A developer is writing a Python inventory reconciliation script. They need to examine each element of a list named `stock` and, for every element, execute a block of code that updates a running total. They do not want the loop to terminate early under any condition. Which statement should be placed at the beginning of the loop body to iterate over every element in order?

Accepted Answer

for item in stock:. Iterating over a list with `for item in stock:` visits every element in order and assigns each value to the loop variable, making it the direct way to process all entries without early exit. The alternatives misuse `range()`, `len()`, or `while` in ways that either raise errors or fail to traverse the list sequentially, so they cannot accomplish the reconciliation task.

Answer

for item in len(stock):

Answer

for item in range(stock):

Answer

while item in stock:

Question 11

A data analyst has a list `readings` of numeric sensor values and needs to build a new list `scaled` that contains each reading multiplied by 2, but only for readings that are positive. Negative and zero readings should be excluded. Which code correctly produces `scaled`?

Accepted Answer

scaled = [r * 2 for r in readings if r > 0]. The correct comprehension uses a filter clause after the for to include only positive readings, then multiplies each by 2 in the expression. This produces a new list containing doubled values for positive readings only, excluding negatives and zeros. It matches the analyst's specification and uses idiomatic Python syntax.

Answer

scaled = [r * 2 for r in readings if r >= 0]

Answer

scaled = [r * 2 if r > 0 for r in readings]

Answer

scaled = [r for r in readings if r > 0] * 2

Question 12

A developer writes a function that assigns a new value to an element of a list passed as an argument. After the function returns, the caller observes that the original list has been modified. The developer wants a second function that appends an item to a list but leaves the caller's list unchanged. Which definition achieves this?

Accepted Answer

def add_item(lst, item):
    lst = lst + [item]
    return lst. Passing a list to a function passes a reference to the same object, so any in-place method such as append, insert, or += alters the caller's data. Only creating a new list object, as with the concatenation lst + [item], avoids mutating the caller's list while still producing an appended result that can be returned.

Answer

def add_item(lst, item):
    lst += [item]
    return lst

Answer

def add_item(lst, item):
    lst.insert(0, item)
    return lst

Answer

def add_item(lst, item):
    lst.append(item)
    return lst

Question 13

A Python developer is building a quiz application. The program stores correct answers in a list named `key` and user responses in a list named `answers`. The developer wants to count how many positions match between the two lists, stopping the comparison as soon as the first mismatch is found so that a diagnostic message can be shown. Which control-flow statement should be used inside the loop to stop iterating immediately when a mismatch occurs?

Accepted Answer

break. The `break` statement exits the nearest enclosing loop immediately, which is precisely what is needed to stop comparing list positions once the first mismatch appears. `continue` only skips one iteration, `pass` does nothing, and `return` leaves the whole function, so none of those produce the desired early loop termination while preserving subsequent code execution.

Answer

return

Answer

continue

Answer

pass

Question 14

A developer needs to store configuration settings as key-value pairs and later retrieve the value for a key that may not exist, providing a default value if the key is missing. Which dictionary method should be used?

Accepted Answer

get(). The get() method safely retrieves a value for a key and returns a default if the key is absent, without altering the dictionary. Other methods either modify the dictionary or do not directly retrieve values, making them unsuitable for a read-only lookup with a fallback.

Answer

pop()

Answer

keys()

Answer

setdefault()

Question 15

A function is defined to accept a variable number of positional arguments and return their sum. The code is:

def total(*args):
    return sum(args)

What is the result of `total(1, 2, 3)`?

Accepted Answer

6. The *args parameter collects the positional arguments into a tuple. The sum function then adds the elements of that tuple. With arguments 1, 2, and 3, the sum is 6. Thus, the function returns 6.

Answer

A tuple `(1, 2, 3)`

Answer

A TypeError is raised.

Answer

0