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?
(A) 4/23
(B) 5/26
(C) 7/26
(D) 8/15
Answer: (B)
Explanation:
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.