An bag contains four yellow balls and two green balls. Find the probability of getting a yellow ball if you. . . (a) . . . randomly choose a ball from the urn. (b) . . . randomly choose and discard two balls and then choose a third. i know how to do part a..it's just 4/6 = 2/3 but for part b, i cant do it because there will be three cases: discarding 2 yellow, discarding 2 green or discarding 1 yellow and 1 green but i should only get 1 answer ???