Quick Answer
The answer is 40.0. This output occurs because Python’s operator precedence dictates that division (`/`) is evaluated before addition (`+`), so the expression `a + b + c / 3` is computed as `10 + 20 + (30 / 3)`, which simplifies to `10 + 20 + 10.0`, yielding `40.0`. Division in Python 3 always returns a float, which is why the result is not an integer. On the Certified Entry-Level Python Programmer PCEP exam, this question tests your understanding of how operator precedence affects arithmetic expressions in Python, a common pitfall for beginners who assume left-to-right evaluation without considering precedence. The trap here is that many learners mistakenly calculate `(10 + 20 + 30) / 3` and get `20.0`, but the absence of parentheses changes the entire outcome. A helpful memory tip is “PEMDAS but with a Python twist”: remember that exponentiation, multiplication, division, and floor division all outrank addition and subtraction, so always check which operator binds tighter before assuming order.
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 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?
20.0
Why wrong: Incorrect: would be correct if (a+b+c)/3.
10.0
Why wrong: Incorrect: c/3 is 10.0, but a and b are added.
40.0
Correct: operator precedence gives 10+20+10.0 = 40.0.
60.0
Why wrong: Incorrect: no operation yields 60.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
40.0
Option C is correct because 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.
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.
20.0
Why it's wrong here
Incorrect: would be correct if (a+b+c)/3.
10.0
Why it's wrong here
Incorrect: c/3 is 10.0, but a and b are added.
40.0
Why this is correct
Correct: operator precedence gives 10+20+10.0 = 40.0.
Related concept
Read the scenario before looking for a memorised answer.
60.0
Why it's wrong here
Incorrect: no operation yields 60.
Common exam traps
Python Institute often tests operator precedence by placing a division operation at the end of an expression without parentheses, tricking candidates into assuming left-to-right evaluation or that the entire sum is divided.
Detailed technical explanation
Python's operator precedence follows the PEMDAS rule: parentheses, exponentiation, multiplication/division (left-to-right), addition/subtraction (left-to-right). Division (`/`) always returns a float in Python 3, even if the operands are integers, which is why the result is 40.0 rather than 40. This behavior differs from Python 2, where `/` performed floor division on integers. In real-world scenarios, forgetting precedence can lead to subtle bugs in financial calculations or data processing pipelines.
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.
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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: 40.0 — Option C is correct because 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.
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 30, 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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