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    				| 1. | If p.m.f. of a d.r.v. X is P(X = x) = \(\frac{x}{n(n + 1)},\) x/n(n + 1), for x = 1, 2, 3, ……, n and = 0, otherwise, then E(X) =(a) \(\frac{n}{1} + \frac{1}{2}\)(b) \(\frac{n}{3} + \frac{1}{6}\)(c) \(\frac{n}{2} + \frac{1}{5}\)(d) \(\frac{n}{1} + \frac{1}{3}\) | 
| Answer» Correct answer is (b) \(\frac{n}{3} + \frac{1}{6}\) | |