CTAL-TM practice question 15 of 30

You are a Test Manager at a company that develops mobile phone applications. Based on historical data in your company, you have calculated the…

You are a Test Manager at a company that develops mobile phone applications. Based on historical data in your company, you have calculated the following average metrics for system testing: • for each 100 LOC (Lines Of Code). 4 test cases are executed • each test case takes on average 15 minutes to execute and check • for each 1000 LOC, 5 defects are found You have used this information to create an estimate for the system testing of a new mobile phone application being developed to submit gas and electricity readings. The application delivered for system testing has 50.000 lines of code. At the end of system testing, 250 defects are discovered. Assume that: • the system test of the new mobile phone application will require the same amount of effort as previous applications • defect density = number of defects/1000 LOC • no new tools or processes have been introduced to the test team Based only on the given information, which one of the following statements is true about this new mobile phone application? SELECT ONE OPTION

Answer options

A: The time taken to run all the estimated tests would be 750 hours.

B: 3000 test cases will be executed during system testing and 250 defects will be found.

C: The actual number of defects found is the same as the estimated number of defects. Correct answer

D: The source code contains a lower defect density than the source code of past applications

Correct Answer:

C. The actual number of defects found is the same as the estimated number of defects.

Explanation

Based on the historical metrics provided, the estimated number of defects for the new application is calculated as (50,000 LOC / 1000) 5 = 250 defects. The scenario states that exactly 250 defects were discovered at the end of system testing. Therefore, the actual number of defects found is exactly the same as the estimated number of defects. The other metrics can be calculated as follows: estimated test cases = (50,000 / 100) 4 = 2000 test cases; estimated time = 2000 15 minutes = 30,000 minutes (or 500 hours).

Why Incorrect

A: The estimated time to run all tests is 500 hours (2000 test cases 15 minutes = 30,000 minutes), not 750 hours. B: The estimated number of test cases to be executed is 2000 (50,000 LOC / 100 4), not 3000. D: The defect density is exactly the same as past applications (250 defects / 50 = 5 defects per 1000 LOC), not lower.

References

1. ISTQB Certified Tester Advanced Level Syllabus - Test Manager (v2012), Section 3.3.2 "Test Estimation", pp. 42-44.

2. Black, R. (2014). Advanced Software Testing - Vol. 2: Guide to the ISTQB Advanced Certification as an Advanced Test Manager. Rocky Nook. Chapter 3 (Test Estimation).

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