Question

If the p.m.f. of a d.r.v. X is P(X = x) = `{{:(x/("n"("n" + 1))",", "for"  x = 1","  2","  3","  .... "," "n"),(0",", "otherwise"):}`, then E(X) = ______

विकल्प

• `"n" + 1/2`

• `"n"/3 + 1/6`

• `"n"/2 + 1/5`

• `"n" + 1/3`

Answer 1

`"n"/3 + 1/6`