Question

There are two bags I and II. Bag I contains 3 white and 4 black balls, and bag II contains 5 white and 6 black balls. One ball is drawn at random from one of the bags and is found to be white. Find the probability that it was drawn from bag I.

Answer 1

Consider W as the white ball, B as the black ball

X as the first bag and Y as the second bag

Assume selecting bags is of equal probability = 1/2

Here we should determine

P (X/W) – Probability of selected white ball is from the first bag

Substituting the values

So we get

= 33/68

Hence, the probability of selected white ball is from the first bag is 33/68.