Aptitude | Probability | Question 3
A box contains 6 black, 5 brown and 2 yellow balls. If 2 balls are selected at random, what is the probability that both are black?
There are total 13 balls in the sample space
Probability of choosing any two of them is 13C2.
There are total 6 black balls and probability of choosing any two of them is 6C2
Therefore the required answer is 6C2/13C2 = 5/26.