A fruit seller buys lemons at 2 for a dollar and sells them at 5 for three dollars. What is his gain percent? a)10%
b)15%
c)20%
d)25%​

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?