a bag contains 3 red , 2 yellow and 4 green balls . 3 balls are drawn randomly . what is the probability that the balls drawn contain balls of different colours ?
"total number of balls = 3 + 2 + 4 = 9 n ( s ) = 9 c 3 = 84 n ( e ) = 3 c 1 * 2 c 1 * 4 c 1 = 3 * 2 * 4 = 24 probability = 24 / 84 = 2 / 7 answer is a"
divide(multiply(choose(4, const_2), choose(add(3, 2), const_1)), choose(add(add(3, 2), 4), 3))