Randomly choose 3 balls from 15 black balls, 6 red balls and 7 blue balls. What is the probability that 2 red balls and 1 black ball are chosen? Solution Case 1: 2 red balls and 1 black ball Total sample space = 28 Select only three by 28C3 ways now we need 2 red and 1 black this can be selected using 15C1 * 6C2 ways Hence the probability will be 15C1 * 6C2 / 28C3 =25/364 second case. none of the three balls chosen in blue then select out of 21 balls 21C3/28C3 = 95/234 exactly two red balls are chosen and no blue balls this implies the thurd ball is black. hence the answer will be same as the one in first case. please rate. require ratings thank you.

1. Randomly choose 3 balls from 15 black balls, 6 red balls and 7 blue balls. What is the probability
that 2 red balls and 1 black ball are chosen?
Solution
Case 1: 2 red balls and 1 black ball Total sample space = 28 Select only three by
28C3 ways now we need 2 red and 1 black this can be selected using 15C1 * 6C2 ways Hence
the probability will be 15C1 * 6C2 / 28C3 =25/364 second case. none of the three balls chosen
in blue then select out of 21 balls 21C3/28C3 = 95/234 exactly two red balls are chosen and no
blue balls this implies the thurd ball is black. hence the answer will be same as the one in first
case. please rate. require ratings thank you