PCEP Practice Test 18 — 15 Questions

Question 1

A company needs to calculate the average of three test scores entered by a user. The scores are integers. The programmer writes the following code:

s1 = input("Enter score 1: ")
s2 = input("Enter score 2: ")
s3 = input("Enter score 3: ")
avg = (s1 + s2 + s3) / 3
print("Average:", avg)

When run, the output is incorrect. What is the most likely cause?

Accepted Answer

The input() function returns strings, so concatenation occurs instead of addition.. The `input()` function in Python always returns a string, even when the user types numbers. The `+` operator on strings performs concatenation (e.g., '5' + '3' + '2' becomes '532'), not numeric addition. Dividing the concatenated string by 3 then causes a `TypeError` (or produces an incorrect result if the string is implicitly converted), so the average calculation fails.

Answer

The division by 3 will cause a ZeroDivisionError because 3 is not a float.

Answer

The division operator / always returns an integer, but the sum is not an integer.

Answer

The variable names s1, s2, s3 are not allowed because they start with a letter.

Question 2

A program needs to read a user's age and print a message if they are 18 or older. Which code snippet correctly accomplishes this?

Accepted Answer

age = int(input('Age: '))
if age >= 18:
    print('Adult'). It uses `int()` to convert the user input to an integer, then compares it with the integer `18` using the `>=` operator. This ensures a proper numeric comparison, and if the condition is true, it prints 'Adult'.

Answer

age = int(input('Age: '))
if age >= '18':
    print('Adult')

Answer

age = input('Age: ')
if age >= 18:
    print('Adult')

Answer

age = input('Age: ')
if age == 18:
    print('Adult')

Question 3

Given 's = "Hello"; t = s[0:3]; print(t)', what is the output?

Accepted Answer

Hel. String slicing in Python uses the syntax `s[start:stop]`, where the stop index is exclusive. For `s = "Hello"`, `s[0:3]` extracts characters from index 0 up to but not including index 3, resulting in indices 0 ('H'), 1 ('e'), and 2 ('l'), giving the substring "Hel".

Answer

ello

Answer

H

Answer

Hell

Question 4

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 5

A developer needs to swap the values of two variables a and b in a single line of code. Which statement correctly accomplishes this?

Accepted Answer

a, b = b, a. Python supports tuple unpacking, allowing the values of variables `a` and `b` to be swapped in a single line: `a, b = b, a`. The right-hand side `b, a` creates a tuple of the current values, which is then unpacked and assigned to the left-hand side variables, effectively swapping them without needing a temporary variable.

Answer

a = b, b = a

Answer

a = b; b = a

Answer

a = b; a = b

Question 6

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 7

A script uses the input() function to get a user's age: age = input('Enter age: '). Later it computes age > 18. This raises a TypeError. What is the root cause?

Accepted Answer

The variable age is a string, not an integer.. The `input()` function in Python always returns a string, regardless of what the user types. When the user enters their age, the variable `age` holds a string like '25', not an integer. Comparing a string to an integer with the `>` operator raises a `TypeError` because Python does not automatically convert strings to numbers for comparison.

Answer

The input() function cannot read numbers.

Answer

The variable age is automatically converted to int.

Answer

The comparison operator > is not valid for strings.

Question 8

Refer to the exhibit. What is the most likely cause of this error?

Accepted Answer

Variable x is used before assignment. The error message indicates that variable 'x' is being referenced before it has been assigned a value. In Python, using a variable that has not been defined yet raises a NameError. Option B correctly identifies this as the cause.

Answer

Variable x is a string

Answer

Variable x is an integer

Answer

Variable x is misspelled

Question 9

A developer wants to output a variable price with two decimal places using formatting. Which line of code will produce 'Price: $12.50' for price = 12.5?

Accepted Answer

print(f'Price: ${price:.2f}'). It uses an f-string with the format specifier `:.2f`, which formats the float `12.5` as a string with exactly two decimal places, producing '12.50'. The f-string then interpolates this into the full string 'Price: $12.50'.

Answer

print('Price: $' + price)

Answer

print('Price: $' + str(round(price, 2)))

Answer

print('Price: $%s' % price)

Question 10

Which of the following is a valid variable name in Python?

Accepted Answer

_count. (_count) is correct because in Python, variable names can start with an underscore, and underscores are allowed anywhere in the name. The name _count follows all Python identifier rules: it starts with a letter or underscore, contains only letters, digits, or underscores, and is not a reserved keyword.

Answer

my-var

Answer

2nd_place

Answer

class

Question 11

Which two of the following are true about Python lists? (Choose two.)

Accepted Answer

Lists can contain elements of different data types.. Option A is correct because Python lists are heterogeneous ordered collections, so a single list may hold elements of different data types (e.g., [1, 'two', 3.0, True]) without any type restriction. Option E is correct because the built-in len() function returns the number of elements in a list, such as len([10, 20, 30]) returning 3. Option B is incorrect because lists are mutable and therefore unhashable, so they cannot be used as dictionary keys (a TypeError is raised). Option C is incorrect because Python uses zero-based indexing, so the first element is at index 0, not 1. Option D is incorrect because lists are mutable: elements can be added, removed, or reassigned in place via methods like append(), remove(), or item assignment.

Answer

Lists can be used as dictionary keys.

Answer

Lists are indexed starting from 1.

Answer

Lists are immutable.

Question 12

A developer writes: total = 2 ** 3 + 4. What is the value of total?

Accepted Answer

12. In Python, the exponentiation operator (**) has higher precedence than addition (+). Therefore, 2 ** 3 is evaluated first, yielding 8. Then 8 + 4 equals 12. Option B is correct.

Answer

16

Answer

14

Answer

10

Question 13

Which TWO of the following are valid variable names in Python?

Accepted Answer

total_sum. Option C (total_sum) is valid because Python identifiers may contain letters, digits, and underscores, and this name starts with a letter and uses only those allowed characters. Option E (_count) is valid because a leading underscore is permitted in Python identifiers, and the rest of the name contains only letters. Option A (my-var) is invalid because the hyphen is not allowed in Python identifiers; it is interpreted as a subtraction operator. Option B (2nd_place) is invalid because identifiers cannot begin with a digit. Option D (for) is invalid because 'for' is a reserved Python keyword and cannot be used as a variable name.

Answer

my-var

Answer

2nd_place

Answer

for

Question 14

A dictionary student = {'name': 'John', 'age': 20}. To safely get the grade with a default of 'N/A', which code should be used?

Accepted Answer

student.get('grade', 'N/A'). The `get()` method of a dictionary safely retrieves the value for a given key, returning a default value (here `'N/A'`) if the key does not exist. This avoids raising a `KeyError` when the key `'grade'` is missing from the dictionary.

Answer

student['grade']

Answer

student.fetch('grade', 'N/A')

Answer

student['grade'] or 'N/A'

Question 15

A program reverses a string using a while loop. The code is:

text = "hello"
reversed_text = ""
index = len(text) - 1
while index > 0:
    reversed_text += text[index]
    index -= 1
print(reversed_text)

It prints 'olle' instead of 'olleh'. What is the error?

Accepted Answer

Change the condition to 'while index >= 0:'. The while loop condition `index > 0` stops when `index` becomes 0, so the character at index 0 (the first character 'h') is never appended to `reversed_text`. Changing the condition to `while index >= 0:` ensures the loop runs for index values from 4 down to 0 inclusive, producing the full reversed string 'olleh'.

Answer

Change the initial index to len(text)

Answer

Use a for loop instead

Answer

Use string slicing: reversed_text = text[::-1]