CTFL_Syll_4.0 Exam Dumps : ISTQB Certified Tester Foundation Level (CTFL) v4.0

In the given state transition diagram, we need to identify the minimum number of test cases required to cover every unique sequence of exactly 4 states/3 transitions starting and ending in the "Inactive" state.

The states are:

Inactive

Active

Alert Mode

Alarm bell rings

Inactive -> Active -> Inactive -> Active -> Inactive

Sequence: Press Button, Enter PIN, Press Button, Enter PIN

Inactive -> Active -> Alert Mode -> Inactive

Sequence: Press Button, Sensor Activated, Enter PIN

Inactive -> Active -> Alert Mode -> Alarm bell rings -> Inactive

Sequence: Press Button, Sensor Activated, Timeout expired, Press Button

Test Case Analysis:These sequences cover every unique combination of exactly 4 states and 3 transitions starting and ending in the "Inactive" state.

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.

This answer is correct because a typical objective of testing is to ensure that a software has been tested using a combination of test techniques, such as black-box, white-box, or experience-based techniques, that are appropriate for the test objectives, test levels, and test types. Testing using a combination of test techniques can increase the effectiveness and efficiency of testing, as different techniques can target different aspects of the software quality, such as functionality, usability, performance, security, reliability, etc. Testing using a combination of test techniques can also reduce the risk of missing defects that could be detected by one technique but not by another. References: ISTQB Foundation Level Syllabus v4.0, Section 2.3.1.1, Section 2.3.2