Posted by Sam on Monday, February 28, 2011 at 8:31pm.
Four balls are selected at random without replacement from an urn containing three white balls and five blue balls. Find the probability that two or three of the balls are white.

math probability  Reiny, Monday, February 28, 2011 at 9:05pm
prob (two are white) = C(4,2)((3/8)^2(5/8)^2
Prob(three are white = C(4,3)(3/8)^3(5/8)
add them up.