Let A be the event that you draw the two headed coin and
Let B be the event that you get two heads then
A box contains 4 fair coins, and one two headed coin. A man selects a coin from the box, tosses it twice, and gets two heads. What is the probability that he selected the two headed coin?
Possible answers: 1/5, 1/3, 1/2, 4/5, 2/3.
My answer was 1/2. Can anyone disprove this?