If the coefficient of rth and (r + 1)th terms in the expansion of (3 + 7x)29 are equal, then r equals
15
21
14
None of these
If in the expansion of (1 + x)m (1 - x)n, the coefficient of x and x2 are 3 and - 6 respectively, then m is
6
9
12
24
The coefficient of xn in the expansion of is
B.
If X is a binomial variate with the range {0, 1, 2, 3, 4, 5, 6} and P(X = 2) = 4P(X = 4), then the parameter p of X is