Question

Rafael is taking a test that contains a section of 12 true-false questions. how many of the possible groups of answers to these questions have exactly 8 correct answers of false?

Answer 1

Answer: There are 495 possible different sets of answers the could contain exactly 8 correct answers of false.

Basically, we are looking for the number of different ways of selecting 8 objects out of a set of 12 objects. Our objects are answers of false and the set is the test.

This is a combination problem. The formula would be:

12! / (8! x 4!) = 495