PCEP Practice Test 9 — 10 Questions

Question 1

A junior developer wrote a function that calculates the average of a list of numbers. Inside the function, they used a variable named 'list' to store the input parameter. Later, they tried to call the built-in list() function to convert a string to a list inside the same function, but it raised a TypeError. The error occurs because the name 'list' now refers to the parameter, not the built-in. The function must be fixed without changing its external behavior. Which solution is the best practice?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Rename the local variable to something else, like 'lst' or 'data'. The best practice is to avoid shadowing built-in names. By renaming the parameter from 'list' to something like 'lst' or 'data', the built-in list() function remains accessible, and the function's external behavior is unchanged. This approach is simple, readable, and follows Python's naming conventions.

Answer

Use the global keyword to refer to the built-in list

Answer

Use the builtins module (import builtins; builtins.list()) to call the built-in

Answer

Remove the local variable and use the input parameter directly

Question 2

Refer to the exhibit. What is the cause of the error?

Accepted Answer

Using + on incompatible types (str and int). The error occurs because the `+` operator is being used between a string and an integer, which are incompatible types in Python. Python does not implicitly convert the integer to a string for concatenation; it raises a `TypeError: unsupported operand type(s) for +: 'str' and 'int'`.

Answer

Division by zero

Answer

Missing import statement

Answer

Variable not defined

Question 3

A developer writes a script to calculate the average of three numbers: avg = (a + b + c) / 3. If a=5, b=10, c=15, what is the data type of avg?

Accepted Answer

float. In Python, the division operator (/) always returns a float, even when dividing integers that result in a whole number. Here, (5 + 10 + 15) / 3 equals 30 / 3, which yields 10.0, a float. Therefore, the data type of avg is float.

Answer

bool

Answer

int

Answer

str

Question 4

What is the type of the result of the expression 5 + 3.0?

Accepted Answer

float. In Python, when an integer (int) and a float are combined using the addition operator, the result is implicitly converted to a float to preserve precision. Since 3.0 is a float, 5 + 3.0 yields 8.0, which is of type float.

Answer

str

Answer

int

Answer

complex

Question 5

What is the result of bool(0) in Python?

Accepted Answer

False. The bool() function in Python converts any value to a Boolean. The integer 0 is considered a falsy value, so bool(0) returns False. This is because Python defines 0, None, empty collections, and False itself as falsy.

Answer

0

Answer

None

Answer

True

Question 6

A beginner writes: x = 10; y = 3; print(x // y). What is the output?

Accepted Answer

3. The // operator in Python performs floor division, which returns the largest integer less than or equal to the result of the division. Since 10 divided by 3 equals 3.333..., the floor of that value is 3, and because both operands are integers, the result is an integer (3), not a float.

Answer

1

Answer

3.0

Answer

3.333

Question 7

A network engineer writes a script to validate IP addresses. The script checks each octet and prints 'Valid' if all octets are between 0 and 255, otherwise 'Invalid'. However, the script always prints 'Invalid' for valid IPs. The code uses a for loop with an else clause. Which logical error is likely?

Accepted Answer

The for loop's else clause executes when the loop completes without break, but the engineer expects else to run when break occurs. In Python, a `for` loop's `else` clause executes only when the loop completes normally (i.e., without hitting a `break`). The engineer likely intended the `else` to run when an invalid octet is found (triggering a `break`), but instead the `else` runs when all octets are valid and the loop finishes without breaking, causing the script to always print 'Invalid' when the validation logic is inverted.

Answer

The list of octets is not properly split

Answer

The condition uses 'or' instead of 'and'

Answer

The else clause is indented incorrectly

Question 8

Which list method modifies the list in place by adding all elements of another iterable to the end?

Accepted Answer

extend(). The `extend()` method modifies the list in place by appending all elements from the provided iterable (e.g., another list, tuple, or string) to the end. It does not return a new list; it mutates the original list directly, which is the behavior described in the question.

Answer

+ operator

Answer

insert()

Answer

append()

Question 9

Which THREE of the following expressions evaluate to the integer 1? (Select three.)

Accepted Answer

int(1.0). Option A, int(1.0), is correct because Python's int() constructor truncates the float 1.0 toward zero, yielding the integer 1. Option B, 2 // 2, is correct because floor division of 2 by 2 produces the integer quotient 1. Option E, 4 % 3, is correct because the modulo operator returns the remainder of 4 divided by 3, which is the integer 1. Option C, True == 1, evaluates to the Boolean True rather than the integer 1, even though True is numerically equal to 1 in Python. Option D, 1 * 1.0, evaluates to the float 1.0, not the integer 1, because multiplying an int by a float promotes the result to float.

Answer

True == 1

Answer

1 * 1.0

Question 10

Which of the following variable names is NOT valid in Python?

Accepted Answer

2nd_place. Python variable names cannot begin with a digit. The name '2nd_place' starts with '2', which violates Python's identifier naming rules. Valid variable names must start with a letter (a-z, A-Z) or an underscore (_), followed by letters, digits, or underscores.

Answer

My_Var

Answer

_myVar

Answer

myVar2