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Testable NFRs for Ticket System
publish date: 2026/06/06 23:08:29.368906 UTC
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Consider writing non-functional requirements for the ticket-issuing system covering reliability and response time. Which of the following are well-written, testable non-functional requirements? Select all that apply.
Correct Answer
(1) The system shall respond to a destination selection within 1.5 seconds of the button press.
(2) The system shall have a mean time between failures (MTBF) of no less than 500 hours of continuous operation.
(3) The system shall complete a full ticket transaction (from start button to ticket issuance) within 45 seconds.
Explanation
Testable NFRs have measurable thresholds: response within 1.5 seconds, MTBF ≥ 500 hours, and transaction within 45 seconds are all verifiable with specific tests. 'The system should be fast', 'reliable', and 'easy to use' are goals — good intentions but not objectively testable.
Reference
Software Engineering, Ian Sommerville, 9th edition