Question

A bag contains 2 red balls, 3 blue balls and 5 green balls.
3 balls are drawn at random. Find the probability that
a) the 3 balls are of different colours
b) 2 balls are of the same colour
c) all the 3 are of the same colour.

Answer 1

a. Pr(three different)=2/10*3/9*5/8

b. Pr(two same)=pr(none same)-pr(threesame)

= Pr(3 different)-3/10*2/9-1/8 - 5/10*4/9*3/8