question_answer 1)

A bag contains 4 red and 4 black balls, another bag contains 2 red and 5 black balls. One of the two bags is selected at random and a ball is drawn from the bag which is found to be red. Find the probability that the ball is drawn from the firs bag. 

Answer:

Let E1, E2 are events of selection of the first and second bag respectively.             Let A = event of getting a red ball                   Required probability = P(E1/A)                   [Baye?s theorem]