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Following a risk-based testing approach you have designed 10 tests to cover a product risk with a high-risk level. You want to estimate, adopting the three-point test estimation technique, the test effort required to reduce the risk level to zero by executing those 10 tests. You made the following three initial estimates: * most optimistic = 6 person hours * most likely = 30 person hours * most pessimistic = 54 person hours Based only on the given information, which of the following answers about the three-point test estimation technique applied to this problem is true?
Correct Answer: A
Explanation The three-point test estimation technique is a method of estimating the test effort based on three initial estimates: the most optimistic, the most likely, and the most pessimistic. The technique uses a weighted average of these three estimates to calculate the final estimate, which is also known as the expected value. The formula for the expected value is: Expected value = (most optimistic + 4 * most likely + most pessimistic) / 6 Using the given values, the expected value is: Expected value = (6 + 4 * 30 + 54) / 6 Expected value = 30 person hours However, the expected value is not the only factor to consider when estimating the test effort. The technique also calculates the standard deviation, which is a measure of the variability or uncertainty of the estimates. The formula for the standard deviation is: Standard deviation = (most pessimistic - most optimistic) / 6 Using the given values, the standard deviation is: Standard deviation = (54 - 6) / 6 Standard deviation = 8 person hours The standard deviation can be used to determine a range of possible values for the test effort, based on a certain level of confidence. For example, using a 68% confidence level, the range is: Expected value ± standard deviation Using the calculated values, the range is: 30±8 person hours Therefore, the final estimate is between 22 person hours and 38 person hours, which is option A. References: ISTQB Certified Tester Foundation Level Syllabus v4.01, Section 2.3.2, page 24-25; ISTQB Glossary v4.02, page 33.
