Question

Suppose that a high school marching band has 112 members. Of these 112 band members, 35 are seniors, 21 play the trumpet, and 8 are seniors who play the trumpet. What is the probability that a randomly selected band member is a senior given that he or she plays the trumpet? Give your answer as a percentage, rounded to one decimal place. What is the probability that a randomly selected band member plays the trumpet given that he or she is a senior?

Answer 1

Part A: 38.1% of the members are seniors that play the trumpet

Part B: 22.9% of the members who are seniors play trumpet

Explanation:

Part A:

8 of the 21 members play trumpet that are seniors

8/21 = .381 or %38.1 of the members

Part B:

8 of the 35 seniors in the marching band play trumpet

8/35 = .229 or %22.9 of the members