ISTQB Updated ISTQB-CTFL Exam Questions and Answers by andy

Equivalence partitioning is a black-box test design technique where inputs to the software or system are divided into groups that are expected to exhibit similar behavior. For an integer field that should accept values from 1 to 15, the valid equivalence class is 1 through 15. The invalid equivalence classes are numbers less than 1 and numbers more than 15. Therefore, option D, "Less than 1, 1 through 15, more than 15," correctly identifies the valid equivalence class along with the two invalid classes, covering all possible input scenarios for the field. Options A, B, and C either do not accurately capture the valid range or incorrectly specify the range boundaries.

Comprehensive and Detailed In-Depth Explanation:

Acceptance criteria 8 states that the system should charge the user on the first business day of the following month. However, the test cycle only verified monthly payments for over a year, without confirming whether payments were processed specifically on the first business day.

(B) is incorrect because the test validated monthly and annual payment options.

(C) is incorrect because not all criteria were fully validated.

(D) is incorrect because OTP verification (6) was tested as part of registration.

Ensuring timely execution of payments (Criteria 8) requires additional validation.

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.