A math teacher gave her class two tests. 25% of the class passed both tests and 42% of the class passed the first test

A math teacher gave her class two tests. 25% of the class passed both tests and 42% of the class passed the first test. What percent of those who passed the first test also passed the second test? Solution: P(A and B) = Probability that a student passed both tests = 0.25 P(A) = Probability that a student passed the first test = 0.42 Find P(B) given that P(A) is true = P(A and B)/P(A) = 25/.42=.6=60% Therefore 60% of those students who passed the first test also passed the second test.