Question

In a math class with 27 students, a test was given the same day that an assignment was due. There were 20 students who passed the test and 18 students who completed the assignment. There were 16 students who passed the test and also completed the assignment. What is the probability that a student failed the test given that they completed the assignment?

Answer 1

We have 18 students who completed the assignment, and 16 of those also passed the test. So 18 − 16 = 2 completed but failed.

Probability(failed | completed) = 2/18 = 1/9 ≈ 11.11%.