PCEP Practice Test 4 — 10 Questions

Question 1

Which of the following will raise a TypeError?

Accepted Answer

t = (1, 2); t[0] = 3. Tuples are immutable in Python; attempting to assign a value to an element using indexing (e.g., `t[0] = 3`) raises a `TypeError` with the message 'tuple' object does not support item assignment. This is a fundamental property of the tuple data type, designed to create fixed sequences that cannot be changed after creation.

Answer

lst = [1, 2]; lst.extend([3, 4])

Answer

x = {1, 2} & {2, 3}

Answer

d = {'a': 1}; d['b'] = 2

Question 2

Which TWO of the following expressions will evaluate to True?

Accepted Answer

3 == 3.0. In Python, the '==' operator compares values, and since integers and floats are compared by numeric value, 3 and 3.0 are numerically equal, so the expression evaluates to True. Option E is correct because 'is' checks object identity, and small integers like 3 are interned by Python, meaning they refer to the same object in memory, so '3 is 3' returns True.

Answer

3 is not 3

Answer

3 > 2 and 2 > 3

Answer

3 != 3.0

Question 3

What is the output of print(10 // 3, 10 % 3)?

Accepted Answer

3 1. The // operator performs floor division, which divides 10 by 3 and discards the fractional part, yielding 3. The % operator returns the remainder of that division, which is 1. The print function outputs both values separated by a space, resulting in '3 1'.

Answer

1 3

Answer

3.33 1

Answer

3 3

Question 4

Which of the following is an immutable data type in Python?

Accepted Answer

tuple. A tuple is immutable because once created, its elements cannot be changed, added, or removed. This is enforced by Python's internal structure: tuples are stored as a fixed-length array of object references, and no methods exist to modify them in place.

Answer

set

Answer

list

Answer

dict

Question 5

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 6

What is the output of the following code?

def greet(name, greeting='Hello'):
    print(greeting, name)

greet('Alice')

Accepted Answer

Hello Alice. The function `greet` has a default parameter `greeting='Hello'`. When called with only one argument (`'Alice'`), the default value is used for `greeting`, so the output is `Hello Alice`. The `print` function outputs both arguments separated by a space.

Answer

Hello

Answer

SyntaxError

Answer

Alice

Question 7

Which TWO operators in Python yield an integer result when applied to two integers?

Accepted Answer

//. The floor division operator (//) always returns an integer result when both operands are integers, discarding any fractional part. For example, 7 // 2 yields 3, not 3.5. This is because floor division performs integer division and truncates toward negative infinity, ensuring the result type is int when both inputs are int.

Answer

**

Answer

*

Answer

/

Question 8

You are maintaining a legacy Python 2.7 script that calculates shipping costs. The script reads weight from user input, then calculates cost as weight * 1.5. Recently, the company upgraded to Python 3.9, and now the script raises a TypeError: can't multiply sequence by non-int of type 'float'. The input line is: weight = input('Enter weight: '). You need to fix the script minimally. Which action should you take?

Accepted Answer

Change the input line to weight = float(input('Enter weight: ')). In Python 3.9, `input()` returns a string, not a number. Multiplying a string by a float raises a TypeError. Option D converts the input to a float immediately, which is the minimal fix because it handles both integer and decimal weights correctly without changing the multiplication logic.

Answer

Use Python 2 style input by importing from __future__

Answer

Change the multiplication to cost = float(weight) * 1.5

Answer

Change the input line to weight = int(input('Enter weight: '))

Question 9

A junior developer is working on a script that processes user data. The script reads a CSV file into a list of dictionaries. Each dictionary represents a user with keys 'name', 'age', and 'email'. The developer needs to filter out users under 18 and store their names in a list. The current code is:

users = [{'name': 'Alice', 'age': 17, 'email': 'alice@example.com'}, {'name': 'Bob', 'age': 22, 'email': 'bob@example.com'}]

minors = []
for user in users:
    if user['age'] < 18:
        minors.append(user['name'])

print(minors)

The code works, but the senior developer says it is not idiomatic and suggests a more concise solution. Which of the following approaches is the best replacement?

Accepted Answer

minors = [user['name'] for user in users if user['age'] < 18]. It uses a list comprehension to directly extract the 'name' field from each user dictionary where the age is under 18, making the code concise and Pythonic. The original code works but is verbose; list comprehensions are the idiomatic Python approach for transforming and filtering iterables in a single readable line.

Answer

minors = []
for i in range(len(users)):
    if users[i]['age'] < 18:
        minors.append(users[i]['name'])

Answer

minors = [user for user in users if user['age'] < 18]

Answer

minors = list(map(lambda u: u['name'], filter(lambda u: u['age'] < 18, users)))