I have some trouble to determine the probability of the following example There are 3 blue balls, 5 red balls, and 4 white balls in a bag of balls. If a person selects two of the balls, what is the probability that the second one is blue given that the first one was white?
A=White B= blue
p[B/A]=p[A and B]/p[A]= p[A]*p[B/A]/p[A]= 3/11
or P[B/A]= 4/12 * 3/11 = 1/11