There are 5 bags three of which each contains 4 white and 2 black balls, and remaining 2 bags each contains 1 white and 4 black ball; a black ball has been drawn, find the chance that it came from first group.	Choose one
A) 2/7	B) 6/35	C) 8/25	D) 5/13	E) 3/5
Please go through my solution and suggest any mistake.   Chances of selecting a black ball from group 1: 1/3----------------------Chances of selecting a black ball from group 2: 4/5   Thus combined probability of section of black ball from group 1:   3/5 x 1/3 = 1/5   Thus combined probability of section of black ball from group 2:   2/5 x 4/5 = 8/25   Out of these chances, chance of occurrence of first case : (1/5) / (1/5 + 8/25) = 5/13   5/13
<result>D</result>
There are 5 bags three of which each contains 4 white and 2 black balls, and remaining 2 bags each contains 1 white and 4 black ball; a black ball has been drawn, find the chance that it came from first group.