In: Math
A box contains 1 fair coin and 1 2-Headed coin. A coin is drawn and flipped several times.
(a) The first flip results in Heads. What is the probability that the coin is fair?
(b) 3 flips result in all Heads. What is the probability that the coin is fair?
(c) 5 flips result in all Heads. What is the probability that the coin is fair?
(d) How many flips of all Heads are required to know with 99.9% accuracy that the coin is not fair?
When we flip a fair
coin, the probability of getting head is 1/2 and getting a tail is
1/2 since it is equally likely that we can getting head or tail in
a trial of flipping a fair coin. If the coin is unfair than we
won't have the same probability for each of two events mentioned
above. Here we have used Bayes theorem for probability. So solution
is as follows.