A bag contains 3 red, 4 white and 5 blue balls. All balls are different. Two balls are drawn at random. The probability that they are of different colour is
As there are 3 +4+5 = 12 balls.
So, 2 balls out of 12 can be drawn in 12C2 ways = 66
Let E denote the event that balls drawn are of different colours
Either the balls will be red-white or white-blue or red-blue.
∴ P(E) =
Hence,
P(E) = 47/66
As our answer matches only with option (a)
∴ Option (a) is the only correct choice.