Question

There are two identical urns containing respectively 6 black and 4 red balls, 2 black and 2 red balls. An urn is chosen at random and a ball is drawn from it, 

(i) find the probability that the ball is black 

(ii) if the ball is black, what is the probability that it is from the first urn?

Answer 1

	Black Balls	Red balls	Total
Urn I	6	4	10
Urn II	2	2	4

(i) Let B be the event getting a black ball.

Now 

(ii) P(I/B)