PCEP Practice Test 4 — 25 Questions

Question 1

A developer writes the following code: x = 5; y = 2; print(x // y). What is the output?

Accepted Answer

2. The floor division operator (//) in Python returns the largest integer less than or equal to the result of the division. Since 5 divided by 2 equals 2.5, the floor is 2, and the result is an integer (int) because both operands are integers. Therefore, the output is 2.

Answer

1

Answer

2.0

Answer

2.5

Question 2

Consider code:
def outer():
    x = 1
    def inner():
        nonlocal x
        x = 2
    inner()
    print(x)
outer()
What is printed?

Accepted Answer

2. The `nonlocal` declaration inside `inner()` binds the variable `x` to the `x` defined in the enclosing `outer()` function. When `inner()` assigns `x = 2`, it modifies that outer `x`, so after `inner()` returns, `print(x)` in `outer()` outputs 2.

Answer

1

Answer

Error

Answer

None

Question 3

Order the steps to create and use a list in Python.

Accepted Answer

1. Create a list with brackets: my_list = []
2. Assign it to a variable: my_list = [1, 2, 3]
3. Access elements by index: print(my_list[0])
4. Modify elements by assignment: my_list[0] = 10
5. Grow the list with methods: my_list.append(4). Lists are created with brackets, assigned to variables, accessed by index, modified by assignment, and grown with methods.

Answer

1. Access elements by index: my_list[0]
2. Create a list with brackets: []
3. Assign it to a variable: my_list = []
4. Modify elements by assignment: my_list[0] = 10
5. Grow the list with methods: my_list.append(4)

Answer

1. Create a list with brackets: my_list = []
2. Access elements by index: print(my_list[0])
3. Assign it to a variable: my_list = [1, 2, 3]
4. Modify elements by assignment: my_list[0] = 10
5. Grow the list with methods: my_list.append(4)

Answer

1. Create a list with brackets: my_list = []
2. Assign it to a variable: my_list = [1, 2, 3]
3. Grow the list with methods: my_list.append(4)
4. Access elements by index: print(my_list[0])
5. Modify elements by assignment: my_list[0] = 10

Question 4

A developer runs the following code: x = 0.1; y = 0.2; print(x + y == 0.3). What is the output and why?

Accepted Answer

False, due to floating-point precision. Floating-point numbers in Python (and most programming languages) are stored in binary (IEEE 754 double-precision), and values like 0.1 and 0.2 cannot be represented exactly. The sum 0.1 + 0.2 yields a result slightly greater than 0.3 (approximately 0.30000000000000004), so the equality comparison returns False.

Answer

False, because the + operator is not defined for floats

Answer

True, because Python rounds to 0.3

Answer

True, because Python uses decimal arithmetic

Question 5

Match each Python data structure to its characteristic.

Accepted Answer

List: mutable, ordered, allows duplicates. Python data structures have distinct properties: lists and tuples are ordered sequences (lists mutable, tuples immutable); sets are unordered and contain unique elements; dictionaries map keys to values. Common confusions include mixing mutability/order between lists and tuples, and assuming sets maintain order.

Answer

List: immutable and ordered

Answer

Set: ordered collection of elements

Question 6

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?

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 7

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 8

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 9

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 10

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 11

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 12

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 13

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 14

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 15

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

Question 16

Which THREE of the following are immutable data types in Python?

Accepted Answer

str. In Python, str (A) is immutable because string objects cannot be modified in place—operations like concatenation or replace() return a new string rather than altering the original. int (B) is immutable since integer objects have a fixed value once created, and arithmetic operations produce new int objects instead of changing existing ones. float (C) is likewise immutable, as floating-point values cannot be changed after creation and any arithmetic yields a new float object. By contrast, list (D) is mutable because elements can be added, removed, or reassigned in place, and dict (E) is mutable because key-value pairs can be inserted, updated, or deleted after the dictionary is created.

Answer

list

Answer

dict

Question 17

Which TWO of the following are Python membership operators?

Accepted Answer

not in. Option B, 'not in', is a Python membership operator that evaluates to True when a specified value is absent from a sequence such as a list, tuple, string, or dictionary, making it correct. Option C, 'in', is likewise a membership operator that tests whether a value exists within a sequence, returning a Boolean result, so it is also correct. The other options are not membership operators: A 'not' is a logical (Boolean) operator, D 'is' is an identity operator that compares object identity, and E 'and' is a logical operator that combines Boolean expressions.

Answer

not

Answer

is

Answer

and

Question 18

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 19

Arrange the steps to read data from a text file in Python.

Accepted Answer

Open the file, read the file contents, process the data, then close the file.. The correct sequence for reading data from a text file in Python is: first open the file using the open() function, then read its contents (e.g., with read() or readlines()), process the data as needed, and finally close the file with close(). Opening establishes a file handle, reading retrieves the data, processing uses it, and closing releases resources. Common mistakes include closing before processing, processing before reading, or reading before opening.

Answer

Open the file, read the file contents, close the file, then process the data.

Answer

Open the file, process the data, read the file contents, then close the file.

Answer

Read the file contents, open the file, process the data, then close the file.

Question 20

Which TWO of the following expressions produce the integer 5?

Accepted Answer

10 // 2. Option B, 10 // 2, is correct because the // operator performs floor division on integers, and 10 divided by 2 yields exactly 5 as an int. Option C, int(5.7), is correct because int() truncates the float toward zero, discarding the fractional part .7 and returning the integer 5. Option A, "5", is a string literal, not an integer, so it does not produce the integer 5. Option D, 5.0, is a floating-point value, not an int. Option E, 10 / 2, uses true division, which in Python 3 returns the float 5.0 rather than the integer 5.

Answer

"5"

Answer

5.0

Answer

10 / 2