The correct answer is 'This is a test. Is this a test?'.count('is') because Python's string method count(substring) returns the number of non-overlapping occurrences of the substring within the string, and here it correctly returns 2, counting the 'is' in 'This' and the standalone 'is', while ignoring the capitalized 'Is' since the method is case-sensitive. On the Certified Associate Python Programmer PCAP exam, this question tests your understanding of string methods and the common trap of forgetting that count() does not perform case-insensitive matching by default—a frequent source of off-by-one errors. To count substring occurrences in Python effectively, remember that count() scans left to right and only counts non-overlapping matches, so overlapping patterns like 'aaa' in 'aaaa' would yield 2, not 3. A handy memory tip: count() is case-conscious, not case-blind—capital letters are invisible to it.
PCAP Strings Practice Question
This PCAP practice question tests your understanding of strings. 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 count the number of occurrences of the substring 'is' in the string 'This is a test. Is this a test?'. Which code correctly performs the count?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
'This is a test. Is this a test?'.count('is')
Option B is correct because Python's string method `count(substring)` returns the number of non-overlapping occurrences of the substring in the string. In 'This is a test. Is this a test?', 'is' appears twice (in 'This' and 'is'), and the method counts them correctly, ignoring case sensitivity (the capitalized 'Is' is not counted).
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
'This is a test. Is this a test?'.split().count('is')
Why it's wrong here
Splitting yields words, 'is' appears only once as a whole word.
✓
'This is a test. Is this a test?'.count('is')
Why this is correct
Correctly counts overlapping? No, count does not count overlapping, but 'is' appears at positions 5 and 17, not overlapping, so returns 2.
Related concept
Read the scenario before looking for a memorised answer.
✗
'This is a test. Is this a test?'.index('is')
Why it's wrong here
index() returns the index of first occurrence or raises error.
✗
'This is a test. Is this a test?'.find('is')
Why it's wrong here
find() returns the index of first occurrence, not count.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the distinction between string methods that return indices (`find`, `index`) versus those that return counts (`count`), and the trap here is that candidates confuse `count()` with `find()` or `index()`, or incorrectly assume `split().count()` works for substring counting.
Detailed technical explanation
How to think about this question
The `str.count()` method uses an efficient algorithm (often a variant of the Boyer-Moore or a simple scan) to count non-overlapping occurrences. It is case-sensitive, so 'Is' (capital I) is not counted. In real-world text processing, such as log parsing or DNA sequence analysis, `count()` is preferred over manual loops for its clarity and performance, though for overlapping matches (e.g., 'aaa'.count('aa') returns 1), a custom loop would be needed.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Strings — This question tests Strings — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 'This is a test. Is this a test?'.count('is') — Option B is correct because Python's string method `count(substring)` returns the number of non-overlapping occurrences of the substring in the string. In 'This is a test. Is this a test?', 'is' appears twice (in 'This' and 'is'), and the method counts them correctly, ignoring case sensitivity (the capitalized 'Is' is not counted).
What should I do if I get this PCAP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Variation 1. What is the output of 'hello'.count('l')?
easy
A.1
B.3
C.0
✓ D.2
Why D: The string method `count('l')` returns the number of non-overlapping occurrences of the substring `'l'` in the string `'hello'`. The string `'hello'` contains the character `'l'` at indices 2 and 3, so the count is 2. Therefore, option D is correct.
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This PCAP 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 PCAP exam.
Question Discussion
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