You are given two coins, one unbiased and the other two-tailed (both sides are tails). Choose a coin at random and toss it once (assume that the probability of choosing the unbiased coin is 3 4). Given that the result is tails, find the probability that the two-tailed coin was chosen

Answer:6/7

Step-by-step explanation:

so basically given observation is u got a tail from a biased coin.

so our favorable case is getting a tail from biased coin.

we will use the probability for it:

p1 = probability of getting choosing biased coin and getting tail = probability of choosing biased coin * probability of tail = 3/4*1

p2 = probability of choosing a fair coin and getting tail = probability of choosing fair coin*probability of getting tail on it = 1/4*1/2 = 1/8

so p (E) = p1 / (p1+p2) = 3/4 / (3/4+1/8) = 7/8