PCEP Data Types, Variables, Basic I/O and Operators Practice Test 6 — 15 Questions

Question 1

A developer needs to store a large collection of unique user IDs (integers) and quickly check if a new ID already exists. Which data type is most appropriate for this task?

Accepted Answer

set. A set is the most appropriate data type because it stores unordered collections of unique elements and provides O(1) average-time complexity for membership testing using the `in` operator. This makes it ideal for quickly checking if a new user ID already exists without needing to manage keys or maintain order.

Answer

dict

Answer

list

Answer

tuple

Question 2

A programmer writes: x = 5; y = x; x = 3; print(y). What is the output?

Accepted Answer

5. In Python, integers are immutable, and the assignment `y = x` copies the reference to the integer object 5, not the variable itself. When `x` is later reassigned to 3, `y` still points to the original integer object 5, so `print(y)` outputs 5.

Answer

3

Answer

8

Answer

None

Question 3

A developer wants to read a floating-point number from user input and compute its square. Which code snippet correctly accomplishes this?

Accepted Answer

num = float(input()); result = num ** 2. It uses `float(input())` to convert the user's input (which is always a string) into a floating-point number, and then computes the square using the exponentiation operator `**`. This ensures that decimal values are handled correctly, which is required for computing the square of a floating-point number.

Answer

num = input(); result = num * num

Answer

result = input() ** 2

Answer

num = int(input()); result = num ** 2

Question 4

A script uses the // operator with negative numbers. For example, -7 // 2 returns -4. The developer expected -3. Which statement best explains this behavior?

Accepted Answer

The // operator performs floor division, which rounds down to the next lower integer.. In Python, the // operator performs floor division, which always rounds down to the next lower integer (toward negative infinity). For -7 // 2, the exact result is -3.5, and floor division rounds down to -4, not -3. This behavior is defined by the Python language specification and differs from truncation toward zero.

Answer

The // operator uses banker's rounding.

Answer

The // operator truncates toward zero for negative numbers.

Answer

The // operator performs integer division with rounding to the nearest even integer.

Question 5

A developer writes a program to calculate the average of three numbers: a=10; b=20; c=30; avg = a + b + c / 3; print(avg). What is the output?

Accepted Answer

40.0. The expression `a + b + c / 3` follows Python's operator precedence: division (`/`) has higher precedence than addition (`+`), so `c / 3` is evaluated first (30 / 3 = 10.0), then the additions are performed left to right: 10 + 20 + 10.0 = 40.0. The result is a float because division always returns a float in Python 3.

Answer

20.0

Answer

10.0

Answer

60.0

Question 6

A programmer needs to swap the values of two variables a and b without using a temporary variable. Which approach works in Python?

Accepted Answer

a, b = b, a. Python supports tuple unpacking, which allows the values of a and b to be swapped in a single atomic operation: a, b = b, a. This works by creating a tuple (b, a) on the right-hand side, then unpacking it into the variables on the left, effectively swapping the values without a temporary variable.

Answer

a = b; b = a

Answer

a = a ^ b; b = a ^ b; a = a ^ b

Answer

a = b + a; b = a - b; a = a - b

Question 7

Which TWO of the following expressions evaluate to True in Python? (Choose two.)

Accepted Answer

1 == True. Option A (1 == True) is correct because Python's bool is a subclass of int, so True has the integer value 1 and the equality comparison returns True. Option B (0 == False) is correct for the same reason: False has the integer value 0, so comparing it to 0 yields True. Option C ('0' == 0) is not correct because a str and an int are different types and are never equal in Python. Option D (2 == True) is not correct because True equals 1, not 2. Option E (None == False) is not correct because None is a distinct object that is only equal to None, not to False.

Answer

'0' == 0

Answer

2 == True

Answer

None == False

Question 8

Which THREE of the following are built-in Python data types? (Choose three.)

Accepted Answer

str. Option A, str, is correct because str is a built-in Python type representing immutable Unicode text strings, created via literals like 'abc' or the str() constructor. Option C, int, is correct because int is a built-in Python type for arbitrary-precision integers, produced by literals like 42 or int(). Option D, list, is correct because list is a built-in Python type for mutable ordered sequences, created with literals like [1, 2] or list(). Option B, boolean, is not a built-in Python type name; the actual built-in type is bool (a subclass of int), so 'boolean' is not a valid Python type. Option E, array, is not a built-in Python type; arrays are provided by the standard-library array module (array.array) or third-party libraries such as NumPy, not as a core built-in type.

Answer

boolean

Answer

array

Question 9

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 10

Order the steps to write a for loop that iterates over a range of numbers.

Accepted Answer

Start with 'for', then variable name, then 'in', then range() with start, stop, step, then colon, then indented loop body. The correct order is to write 'for', then the loop variable, then 'in', then the range() function with appropriate arguments, then a colon, and finally an indented block containing the statements to repeat. This structure defines a for loop that iterates over a sequence generated by range().

Answer

Start with range(), then 'for', then variable name, then 'in', then colon, then indented loop body

Answer

Start with 'for', then variable name, then colon, then 'in', then range(), then indented loop body

Answer

Start with 'for', then 'in', then variable name, then range(), then colon, then indented loop body

Question 11

Order the steps to debug a Python script using print statements.

Accepted Answer

1. Insert print statements, 2. Run the script, 3. Analyze the output, 4. Remove print statements. Debugging with print involves inserting prints, running, analyzing, and cleaning up.

Answer

1. Insert print statements, 2. Remove print statements, 3. Run the script, 4. Analyze the output

Answer

1. Run the script, 2. Insert print statements, 3. Analyze the output, 4. Remove print statements

Answer

1. Analyze the output, 2. Insert print statements, 3. Run the script, 4. Remove print statements

Question 12

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 13

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.

Question 14

Which of the following is a valid Python variable name?

Accepted Answer

_var. (_var) is correct because Python variable names must start with a letter or an underscore, and can contain letters, digits, or underscores. The underscore is a valid starting character, making _var a legal identifier.

Answer

2var

Answer

my-var

Answer

var$name

Question 15

A program uses 'x = 3.14' and 'y = int(x)'. What is the value of y?

Accepted Answer

3. The int() function in Python truncates the decimal part of a float, converting 3.14 to the integer 3. It does not round to the nearest whole number.

Answer

4

Answer

3.14

Answer

Error