If the coefficients of rth and (r + 1)th terms in the expansion of (3 + 7x)29 are equal, then r is equal to
14
15
18
21
Suppose X follows a binomial distribution with parameters n and p, where 0 < p < 1. If is independent of n for every r, then p is equal to
A fair coin is tossed 100 times. The probability of getting tails an odd number of times is
A.