A bag contains 4 red balls, 6 green balls and 5 blue balls ...
Description for Correct answer: Total number of balls = 4 + 6 + 5 = 15 Total possible outcomes = selection of 3 bails out of 15 balls = ( Large ^{15}C_{3} = frac{15 times 14 times 13}{1 times 2 times 3} ) = 455 . Total favourable outcomes = selection of 2 balls out of 6 green balls and selection of 1 ball out of 5 blue balls = ( Large 6_{C_{2}} times ^{5}C_{2} = frac{6 times .