a bag contains 3 red , 5 yellow and 7 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 + 5 + 7 = 15 n ( s ) = 15 c 3 = 455 n ( e ) = 3 c 1 * 5 c 1 * 7 c 1 = 105 probability = 105 / 455 = 3 / 13 answer is c"
divide(multiply(choose(const_4.0, const_2), choose(add(const_3.0, 5), const_1)), choose(add(add(3, 5), 7), 3))