kh kh SolutionLet A represents ball taken from second bin is

Let A represents ball taken from second bin is white

let B represents ball taken from first bin is black

let C represents ball taken from first bin is white

=>
total number of balls in first bin = 8+ 12 = 20
number of balck balls in first bin = 12
number of white balls in first bin = 8

P(B) = 12/20 = 0.6

P(C) = 8/20 = 0.4

after putting black ball from first bin in second bin

total number of balls in second bin = 4 + 6 + 1 = 11
number of white balls in second bin = 4

P(A/B) = 4/11

if the ball drawn from first bin is white
total number of balls in second bin = 4 + 6 + 1 = 11
number of white balls in second bin = 5

P(A/C) = 5/11

by total probabilty formula

P(A) = P(A/B) P(B) + P(A/C) P(C)

= 4/11 * 0.6 + 5/11 * 0.4

= 4.4/11

= 0.4