Question

It is not known whether a coin is fair or infair. If the coin is fair, the probability of a tail is 0.5, bt if the coin is unfair, the probability of a tail is 0.1. If the probability of a fair coin is 0.8 and the probability of a unfair coin is 0.2, the coin is tossed once, and a tail is the result: 1. What is the probability that the coin is fair. 2. What is the probability that the coin is infair.