Answer: 0.3023
Step-by-step explanation:
86 band members
26 are senior, 17 plays trumpet. If 4 are seniors and play trumpet, we solve this using the bayes theorem of conditional probability.
Probability of choosing band member that plays trumpet =17/86 = 2/43.
Probability of choosing a senior that plays trumpet = 4/26
Probability that a chosen member is a senior given that he plays trumpet = (2/43)/(4/26)
= 0.3023.