One hundred identical coins each with probability p of showing up head are tossed. If 0 < p < 1 and the probability of heads showing on 50 coins is equals to that of heads on 51 coins. Then the value of p, is?
Correct Answer: 51/101
Explanation:
Let N be the number of coins showing heads.
∴ Probability when N equal to 50 = Probability when N equal to 51
⇒ 100C50 x P 50 x (1 - p)50 = 100C51 x (1 - p)49
⇒ p = 51/101
