Question

There are two coins. One of them is a biased coin such that P (head): P (tail) is 1 : 3 and the other coin is a fair coin. A coin is selected at random and tossed once. If the coin showed head, then find the probability that it is a biased coin.​

Answer 1

Explanation:

Let B be the event that the selected coin is biased, and F be the event that the selected coin is fair. Let H be the event that the coin toss shows a head.

We want to find P(B|H), the probability that the selected coin is biased given that the coin toss shows a head. By Bayes' theorem, we have:

P(B|H) = P(H|B) * P(B) / P(H)

We know that P(H|B) = 1/4 (since the biased coin has a probability of 1/4 of showing a head), and that P(B) = 1/2 (since there are two coins, one of which is biased).

To find P(H), we can use the law of total probability:

P(H) = P(H|B) * P(B) + P(H|F) * P(F)

P(H) = (1/4) * (1/2) + (1/2) * (1/2)

P(H) = 3/8

Putting it all together:

P(B|H) = P(H|B) * P(B) / P(H)

P(B|H) = (1/4) * (1/2) / (3/8)

P(B|H) = 1/3

Therefore, the probability that the selected coin is biased given that the coin toss shows a head is 1/3.