The probability that a teacher will give an unannounced test during any class meeting is 1/5. If a student is absent twice, then the probability that…

The chance of a test in one class is 1/5, so the chance of no test is 4/5.

The chance of no test in both classes is 4/5 × 4/5 = 16/25.

Missing at least one test is the opposite of missing none. So the probability is 1 – 16/25 = 9/25.