PCEP Practice Test 5 — 25 Questions

Question 1

A dictionary: d = {1: 'a', 2: 'b', 3: 'c'}. Which code will cause a KeyError?

Accepted Answer

d[4]. Accessing a dictionary key that does not exist using square bracket notation (d[4]) raises a KeyError. Since the dictionary d has keys 1, 2, and 3, the key 4 is absent, so d[4] triggers the error.

Answer

d.get(4)

Answer

if 4 in d: d[4]

Answer

d.setdefault(4, 'd')

Question 2

A QA engineer needs to run a test 5 times. Which loop construct is most appropriate?

Accepted Answer

for i in range(5): .... The `for i in range(5)` loop is the most idiomatic and concise way to repeat an action a fixed number of times (5 iterations) in Python. The `range(5)` generates a sequence from 0 to 4, and the loop body executes exactly 5 times, which directly matches the requirement to run a test 5 times without needing manual counter management.

Answer

do: ... while counter < 5

Answer

while counter < 5: ... counter += 1

Answer

def repeat(): ... repeat()

Question 3

A junior developer created a Python script to calculate the average of three quiz scores entered by the user. The script reads three numbers using input(), converts them to float, calculates the sum, and divides by 3. However, when a user enters a non-numeric value like 'ten', the script crashes with a ValueError. The developer needs to modify the script to handle such errors gracefully, allowing the user to re-enter the invalid input until a valid number is provided. Which approach should the developer implement to meet this requirement most effectively while following Python best practices?

Accepted Answer

Implement a while True loop that attempts to convert the input inside a try block. If successful, break out of the loop; if ValueError occurs, print an error message and continue the loop.. It uses a `while True` loop with a `try` block to repeatedly attempt conversion of user input to `float`. If a `ValueError` is raised (e.g., for non-numeric input like 'ten'), the exception is caught, an error message is printed, and the loop continues until valid input is provided. This pattern follows Python best practices for input validation by separating the conversion logic from the loop control and avoiding reliance on fragile string checks like `.isdigit()`.

Answer

Use an if statement to check if the input is numeric using .isdigit(), and if not, ask again.

Answer

Use a try-except block to catch ValueError and prompt the user again, looping until valid input is provided.

Answer

Use a function that returns a default value of 0 if the input is invalid, to avoid script crashes.

Question 4

You are writing a script to parse a log file. Each line in the log contains a timestamp and a message separated by a colon. You need to extract only the messages that contain the word 'ERROR'. The script uses a list comprehension to filter lines. However, the script crashes with a 'ValueError: not enough values to unpack' when processing some lines. The code is:

lines = ['2024-01-01 12:00:00: INFO: all good', '2024-01-01 12:01:00: ERROR: something wrong']
errors = [msg for timestamp, msg in line.split(': ') for line in lines if 'ERROR' in msg]

What is the correct fix?

Accepted Answer

Rewrite as: [msg for line in lines if 'ERROR' in line for msg in [line.split(': ')[1]]]. It properly separates the filtering and unpacking steps. The original code attempts to unpack each line into timestamp and msg using `line.split(': ')`, but some lines may not contain exactly two parts after splitting (e.g., if the colon is missing or there are extra colons), causing a ValueError. Option D first filters lines containing 'ERROR', then safely extracts the message part by splitting and taking index [1] inside a nested comprehension, avoiding the unpacking error.

Answer

Rewrite as: [line for line in lines if 'ERROR' in line]

Answer

Change the list to a dictionary

Answer

Swap the order of the for clauses to: [msg for line in lines for timestamp, msg in line.split(': ') if 'ERROR' in msg]

Question 5

What is the data type of z after executing z = 10 / 2?

Accepted Answer

float. Float because in Python, the / operator always performs true division and returns a float, regardless of the operands. This is a fundamental concept tested in the PCEP exam to distinguish between / and //.

Answer

bool

Answer

int

Answer

str

Question 6

You are a junior developer at a logistics company. Your team is building a system to calculate shipping costs based on package weight. The system reads weight from user input. A colleague wrote the following code: weight = input('Enter weight in kg: '); cost = weight * 2.5; print('Shipping cost:', cost). However, when testing with weight 10, the output is 'Shipping cost: 10101010101010101010' (the string '10' repeated 2.5 times? Actually, 2.5 is float, but string multiplied by float causes TypeError? Wait, string * float raises TypeError. But the symptom described suggests the code runs but produces unexpected output. Let me re-read: The output shows '10101010101010101010' which is the string '10' repeated 10 times? That would happen if weight is string and multiplied by int 10. But the code multiplies by 2.5. Actually, string * float raises TypeError, so the code would crash. The symptom must be plausible. Let me adjust: The code actually has weight = input(...), then cost = weight * 2.5, but if weight is '10', then '10' * 2.5 raises TypeError. So the symptom cannot be that output. I need to fix the stem to make sense. Instead, let's say the code is: weight = input('Enter weight: '); cost = float(weight) * 2.5; print('Cost:', cost). But then no issue. I'll create a scenario where the developer forgot to convert input to float, and then tries to multiply string by float, which causes TypeError. The correct action is to convert input to float. I'll adjust the stem accordingly. Let me rewrite the stem properly.

Stem: You are a developer at a shipping company. The system calculates shipping cost as weight (kg) times rate 2.5. A colleague wrote: weight = input('Enter weight: '); cost = weight * 2.5; print('Cost:', cost). When testing with weight 10, the program crashes with TypeError. Which action should you take to fix the code?

Accepted Answer

Change weight = float(input('Enter weight: ')). `input()` always returns a string, and multiplying a string by a float (2.5) raises a `TypeError`. Converting the input to `float` ensures the multiplication is numeric, allowing decimal weights and producing the correct shipping cost.

Answer

Change weight = int(input('Enter weight: '))

Answer

Change cost = weight * 2.5 and catch TypeError

Answer

Change cost = int(weight) * 2.5

Question 7

Given the following code, which of the following statements are true after execution? (Choose three.)

x = 10
y = 3.0
z = x / y
w = x // y

Accepted Answer

The expression x % y is valid.. The modulo operator % works with both integers and floats in Python. Here, x is an int and y is a float, so x % y is valid and returns a float result (the remainder of the division).

Answer

The type of w is int.

Answer

The expression x / y returns an integer.

Question 8

Which FOUR of the following are correct uses of the print() function?

Accepted Answer

print('Hello', 'World', sep='-'). Options B, C, D, and E are all correct uses of the print() function in Python 3. Option B demonstrates the use of the sep parameter to set a custom separator between arguments. Option C shows printing two string arguments separated by the default space. Option D shows printing a single string. Option E shows printing a string and an integer, which is perfectly valid; the print() function automatically converts non-string arguments to strings. Option A is incorrect because it uses the Python 2 print statement syntax (missing parentheses) and will raise a SyntaxError in Python 3.

Answer

print 'Hello'

Question 9

An application requires different messages based on temperature. Given:
temp = 25
if temp > 30:
    print('Hot')
elif temp > 20:
    print('Warm')
else:
    print('Cool')
What is the output?

Accepted Answer

Warm. The condition `temp > 30` is False (25 is not greater than 30), so the first `if` block is skipped. The `elif temp > 20` condition is True (25 > 20), so the `print('Warm')` statement executes, outputting 'Warm'. Option D is correct.

Answer

No output

Answer

Hot

Answer

Cool

Question 10

Given x = 5, which of the following assignments will cause a runtime error?

Accepted Answer

x //= 0. Division by zero is undefined in Python, and the floor division assignment operator `//=` with a divisor of 0 raises a `ZeroDivisionError` at runtime. The other operators (`**=`, `-=`, `+=`) perform valid arithmetic on the integer 5 and do not cause errors.

Answer

x **= 2

Answer

x -= 3

Answer

x += 2

Question 11

Which of the following are valid Python variable names? (Choose two.)

Accepted Answer

data_1. (data_1) is correct because Python variable names can contain letters, digits, and underscores, but must not start with a digit. 'data_1' starts with a letter and includes an underscore and digit, all of which are allowed.

Answer

for

Answer

2nd_place

Answer

my-var

Question 12

Which THREE of the following are valid Python variable names?

Accepted Answer

myVar2. Python variable names must start with a letter or underscore, and can contain letters, digits, and underscores. 'myVar2' begins with a letter and uses only valid characters, making it a legal identifier.

Answer

my-var

Answer

2ndValue

Question 13

What is the output of the code in the exhibit?

Accepted Answer

[1, 10, 20, 4, 5]. The code uses list slice assignment to replace the elements at indices 1 and 2 (the second and third elements) with the list [10, 20]. Starting from [1, 2, 3, 4, 5], after the assignment lst[1:3] = [10, 20], the list becomes [1, 10, 20, 4, 5]. This matches option B.

Answer

[1, 2, 10, 20, 5]

Answer

[1, 2, 3, 10, 20, 4, 5]

Answer

[1, 10, 20, 3, 4, 5]

Question 14

Which two of the following expressions return the value 5? (Choose two.)

Accepted Answer

10 // 2. (10 // 2) uses floor division, which divides 10 by 2 and returns the integer quotient 5. This is correct because floor division in Python discards any fractional remainder, yielding an exact integer result.

Answer

10 % 5

Answer

10 ** 0

Answer

10 / 2

Question 15

You are a developer in a company that runs a Python script daily to generate reports. The script uses the os module to list files in a directory and process each. Recently, after a server migration, the script fails with 'PermissionError: [Errno 13] Permission denied'. The script runs under a service account that has read/write access to most folders, but the migration changed the permissions on certain subdirectories. The error is intermittent, occurring only for some files. You need to fix the script to continue processing other files even if one fails. Which approach should you take?

Accepted Answer

Use a try-except block inside the loop to catch PermissionError for each file and continue.. By placing a try-except block inside the loop that catches PermissionError specifically, the script can skip the problematic file and continue processing the remaining files. This approach handles the intermittent permission errors gracefully without halting the entire script. Option B is wrong because catching all exceptions silently would mask other critical errors (e.g., bugs in the processing logic). Option C is wrong because os.access() checks may not fully reflect actual runtime permissions due to race conditions and platform-specific behavior, and it requires additional calls that could still fail. Option D is wrong because it relies on external action and does not address the need for the script to be resilient to such errors.

Answer

Wrap the entire processing loop in a try-except that catches all exceptions and passes silently.

Answer

Before processing each file, use os.access() to check permissions and skip if not accessible.

Answer

Ask the server administrator to grant full permissions to the service account on all directories.

Question 16

Which TWO of the following are valid ways to comment in Python?

Accepted Answer

# This is a comment. The hash symbol (#) is the standard syntax for single-line comments in Python. Everything after # on that line is ignored by the Python interpreter, making it a valid comment.

Answer

$ This is a comment

Answer

/* This is a comment */

Answer

// This is a comment

Question 17

Order the steps to define and call a function in Python.

Accepted Answer

1. Define function using def keyword, 2. Optionally specify parameters in parentheses, 3. Write the indented function body, 4. Call the function by its name.. Function definition starts with def, then the body, parameters are optional, and calling the function executes it.

Answer

1. Write the indented function body, 2. Define function using def keyword, 3. Optionally specify parameters in parentheses, 4. Call the function by its name.

Answer

1. Define function using def keyword, 2. Write the indented function body, 3. Optionally specify parameters in parentheses, 4. Call the function by its name.

Answer

1. Call the function by its name, 2. Define function using def keyword, 3. Optionally specify parameters in parentheses, 4. Write the indented function body.

Question 18

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 19

Which TWO statements correctly describe Python's dynamic typing?

Accepted Answer

The interpreter infers the type from the assigned value.. Python's dynamic typing means the interpreter determines the type of a variable at runtime based on the value assigned to it. You do not need to declare the type explicitly; the type is inferred from the object the variable references.

Answer

Variable types must be declared before use.

Answer

Python checks types only at compile time.

Answer

A variable's type is fixed once assigned.

Question 20

Match each Python control flow statement to its purpose.

Accepted Answer

break: Exits the loop immediately.. The correct matches: break exits the loop, continue skips to next iteration, pass does nothing, else runs after normal loop completion. Common confusions include swapping break and continue, or confusing else with pass.

Answer

break: Skips the rest of the current iteration and moves to the next.

Answer

else (in loop): Does nothing; used as a placeholder.