for the first draw 20 balls in the box
for the second there are 19
the rest is obvious.
For example both white
ball one: 10/20 =1/2
ball two: 9/19
so
(1/2)(9/19) = 9/38
ii) A box contains 10 white, 7 black and 3 green balls. 2 balls are drawn at random. Find out the probability that: a) both are white
b) one is white and another is green
c) one is black and another is green
1 answer