How many cases are left when this decision table is collapsed?

Consider the following decision table:

This decision table has been created to test the following specification: Persons that study at a university (C1) and have parents whose total annual income is less than 30.000 (C2), receive a scholarship In in addition to these qualifications, if they also live away from home (C3), they receive an addition to their scholarship (A2)

How many cases are left when this decision table is collapsed?
A . 1
B . 2
C . 4
D . 5

View Answer

Answer: B

Explanation:

A decision table is collapsed when duplicate or impossible cases are removed. In this decision table, there are two duplicate cases: column 2 and column 4 have the same actions (A1 and A2), and column 5 and column 6 have the same action (A1). There are also two impossible cases: column 7 and column 8 have no actions, which means that there is no outcome for these combinations of conditions. Therefore, after collapsing the decision table, only two cases are left: column 1 and column 3, which have different actions (A1 and A2 for column 1, and A1 for column 3).

Reference = ISTQB Certified Tester Advanced Level Syllabus Technical Test Analyst1, page 2 Decision Table-Based Testing2, section “Don’t Care Entries and Rule Counts”

A Guide on Building Decision Tables3, section “How to ensure that the Table is Complete?”