CTFL-PT practice question 3 of 10

You have been asked to test the performance of a software and system update to a North American mobile trivia quiz game application. The quiz app is…

Full set: 40 questions
You have been asked to test the performance of a software and system update to a North American mobile trivia quiz game application. The quiz app is available on major app stores serving English- speaking users. The number of concurrent users planned for is 5 million. Winning quiz participants are promised a share of an allocated cash prize Once participants start playing, their quiz sessions must not be lost especially if all previous questions were answered correctly. The application owner wants to ensure that 99% of quiz sessions are maintained (up to 4 95 million sessions) until the last answer has been successfully recorded. An essential operational profile you identified is the quiz participant. Your operational profile discovery efforts have yielded a number of profile attributes. A quiz participant will answer twelve questions if they manage to answer the first eleven correctly Every user is made aware of a new question nearly simultaneously. The quiz user has limited time to respond using a mobile application. They are unable to respond to subsequent questions after they incorrectly answer a question. However, the quiz participant continues to see new questions even though they may have responded incorrectly to a previous question If they manage to answer all twelve questions correctly, the quiz application notifies them that they have tentatively won (subject to formal verification) an equal share of a cash prize of an amount set for the particular quiz event In addition to this individualized interaction, a broadcast video stream is presented in the quiz app providing entertaining commentary quiz event coordination, event status and answer explanations. The average quiz event duration when measured from when the first question is presented to the last answer is reviewed is fifteen minutes. Over the fifteen minutes, twelve questions are presented to quiz participants. After making the following assumptions: 1. Questions must be responded to within a four second window; 2. Question responses will be sent evenly across this window of time (resulting in an average responder time of two seconds); 3. The designed maximum number of concurrent users will attempt the first question; 4. There will be no functional issues when handling the load. 5. The average time from response reception to database commitment is 1000 milliseconds under maximum concurrent usage. What is the approximate maximum average system throughput if that assumptions hold?
Answer options
A: 1.667 million transactions/second
B: 1 million transactions/second Correct answer
C: 1 million transactions/millisecond
D: 200.000 transactions/second
Correct Answer:
B. 1 million transactions/second
Explanation

System throughput is defined as the number of transactions a system can process per unit of time. The problem states that 5 million concurrent users will submit a response within a 4-second window. The responses are sent evenly across this time period. The calculation for the average system throughput is: Throughput = Total Transactions / Time Period Throughput = 5,000,000 transactions / 4 seconds = 1,250,000 transactions/second. This calculated value is 1.25 million transactions/second. Of the options provided, 1 million transactions/second (Option B) is the closest approximate value. Assumption 4 implies system throughput must match the user load.

Why Incorrect

A. This value would require the 5 million transactions to occur in 3 seconds (5M / 1.667M ≈ 3s), which contradicts the given 4-second window.
C. The unit "transactions/millisecond" is incorrect and represents an implausibly high rate (equivalent to 1 billion transactions/second) for this application.
D. This throughput is significantly lower than the calculated arrival rate of 1.25 million transactions/second, underestimating the required system capacity. ---

References

1. ISTQB® Certified Tester Foundation Level Performance Testing Syllabus Version 1.0 (2018). Section 2.2.1, "Performance Test Types and an Associated Non-functional Requirement," defines Throughput: "The number of transactions or requests per unit of time that a system can process." The calculation performed directly applies this definition.

2. Jain, R. (1991). The Art of Computer Systems Performance Analysis: Techniques for Experimental Design, Measurement, Simulation, and Modeling. Wiley. Chapter 3, "Commonly Used Performance Metrics," defines throughput (or capacity) as the rate at which requests can be serviced by the system. The question requires calculating this rate based on user load.

3. Smith, C. U., & Williams, L. G. (2002). Performance Solutions: A Practical Guide to Creating Responsive, Scalable Software. Addison-Wesley. Chapter 2, "Fundamentals of Performance," discusses key performance metrics, including throughput, which is calculated as the number of completed tasks over a time interval, aligning with the provided explanation.

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