This PCEP practice question tests your understanding of data types, variables, basic i/o and operators. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer needs to check if a variable x is between 10 and 20 (inclusive). Which expression is correct?
x > 10 and x < 20
Why wrong: Excludes the boundaries.
x < 10 and x < 20
Why wrong: This is equivalent to x < 10, not the range.
10 <= x <= 20
Chained comparison works exactly as desired.
x >= 10 or x <= 20
Why wrong: This is always true for any x.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
10 <= x <= 20
Option C is correct because Python supports chained comparison operators, allowing `10 <= x <= 20` to evaluate whether `x` is between 10 and 20 inclusive. This expression is equivalent to `(10 <= x) and (x <= 20)`, which checks both boundaries simultaneously.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
x > 10 and x < 20
Why it's wrong here
Excludes the boundaries.
x < 10 and x < 20
Why it's wrong here
This is equivalent to x < 10, not the range.
10 <= x <= 20
Why this is correct
Chained comparison works exactly as desired.
Related concept
Read the scenario before looking for a memorised answer.
x >= 10 or x <= 20
Why it's wrong here
This is always true for any x.
Common exam traps
The trap here is that candidates often confuse inclusive vs. exclusive boundaries and select Option A with strict inequalities, or they misunderstand that `or` (Option D) creates a condition that is always true, failing to recognize the need for `and` logic.
Detailed technical explanation
Chained comparisons in Python are evaluated as a single expression with short-circuit semantics, meaning `10 <= x <= 20` is not simply syntactic sugar but is implemented at the bytecode level to evaluate each comparison only once. This feature is unique to Python and differs from languages like C or Java, where such chaining would require explicit `&&` operators. In real-world scenarios, chained comparisons improve readability and reduce the risk of off-by-one errors when validating input ranges, such as checking if a user's age falls within a valid range for a service.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the PCEP exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Data Types, Variables, Basic I/O and Operators — This question tests Data Types, Variables, Basic I/O and Operators — Read the scenario before looking for a memorised answer..
The correct answer is: 10 <= x <= 20 — Option C is correct because Python supports chained comparison operators, allowing `10 <= x <= 20` to evaluate whether `x` is between 10 and 20 inclusive. This expression is equivalent to `(10 <= x) and (x <= 20)`, which checks both boundaries simultaneously.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This PCEP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCEP exam.
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