- A
Remove the __init__ method from SavingsAccount entirely and rely on the default __init__ from Account.
Why wrong: This would fail because interest_rate would not be set; also, the caller expects three arguments.
- B
Manually assign self.account_number and self.balance in SavingsAccount.__init__ before assigning interest_rate.
Why wrong: This duplicates code and violates the DRY principle; it also requires maintenance if Account changes.
- C
Call super().__init__(account_number, balance) as the first line in SavingsAccount.__init__, then assign self.interest_rate = rate.
This correctly delegates to the base class and adds the new attribute.
- D
Define balance as a class attribute in Account with a default value and remove it from __init__.
Why wrong: This changes the design: balance is per-instance and must be set at creation; a class attribute would be shared incorrectly.
Quick Answer
The answer is to call super().__init__(account_number, balance) as the first line in SavingsAccount.__init__, then assign self.interest_rate = rate. This fix is correct because Python's inheritance requires the subclass to explicitly invoke the parent class's __init__ method to initialize inherited attributes like account_number and balance; without this call, the subclass object never runs the base class constructor, leaving those attributes undefined and triggering an AttributeError when accessed. On the Certified Associate Python Programmer PCAP exam, this tests your understanding of constructor chaining and the super() function, a common trap where candidates assume attributes are automatically inherited without initialization. The key insight is that __init__ is not automatically inherited—you must chain it manually to avoid code duplication and ensure all parent attributes exist. Memory tip: think of super().__init__ as the "handshake" that passes the baton from child to parent constructor before adding your own unique attributes.
PCAP Object-Oriented Programming Practice Question
This PCAP practice question tests your understanding of object-oriented programming. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 team is developing a banking system in Python. They have a base class Account with attributes account_number and balance, and a method __init__(self, account_number, balance) that initializes these attributes. They then create a subclass SavingsAccount that adds an attribute interest_rate. In SavingsAccount's __init__, they assign self.interest_rate = rate but do not call super().__init__. When they instantiate SavingsAccount('12345', 1000, 0.02) and attempt to print(balance), an AttributeError occurs: 'SavingsAccount' object has no attribute 'balance'. What is the most appropriate fix to ensure that the SavingsAccount includes balance and account_number without code duplication?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Call super().__init__(account_number, balance) as the first line in SavingsAccount.__init__, then assign self.interest_rate = rate.
The fix is to call super().__init__ to reuse the base class initialization and then add the subclass-specific attribute. Option A duplicates code, option C changes the architecture unnecessarily, and option D removes necessary initialization.
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.
- ✗
Remove the __init__ method from SavingsAccount entirely and rely on the default __init__ from Account.
Why it's wrong here
This would fail because interest_rate would not be set; also, the caller expects three arguments.
- ✗
Manually assign self.account_number and self.balance in SavingsAccount.__init__ before assigning interest_rate.
Why it's wrong here
This duplicates code and violates the DRY principle; it also requires maintenance if Account changes.
- ✓
Call super().__init__(account_number, balance) as the first line in SavingsAccount.__init__, then assign self.interest_rate = rate.
Why this is correct
This correctly delegates to the base class and adds the new attribute.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Define balance as a class attribute in Account with a default value and remove it from __init__.
Why it's wrong here
This changes the design: balance is per-instance and must be set at creation; a class attribute would be shared incorrectly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which PCAP exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Questions learners often ask
What does this PCAP question test?
Object-Oriented Programming — This question tests Object-Oriented Programming — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Call super().__init__(account_number, balance) as the first line in SavingsAccount.__init__, then assign self.interest_rate = rate. — The fix is to call super().__init__ to reuse the base class initialization and then add the subclass-specific attribute. Option A duplicates code, option C changes the architecture unnecessarily, and option D removes necessary initialization.
What should I do if I get this PCAP question wrong?
Identify which PCAP exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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