Math
posted by Mary on .
A box contains 4 red cubes, 3 blue cubes, 2 green cubes, and 1 yellow cube. You pick two cubes at random, replacing each after you pick. Find the probability of each compound event.

possible events:
RR RB RG RY
BB BG BY
GG GY
YY
(The order does not matter)
I will do one of them, you do the rest
Prob(B or G) = C(3,1)*C(2,1)/C(10,2) = 6/45 = 2/15
or
Prob(BG) = (3/10)(2/9) = 6/90
prob (GB) = (2/10)(3/9) = 6/90
prob (B or G) = 6/90 + 6/90 = 6/45