Question

If X is a random variable with probability mass function

P(x) = kx ,  x=1,2,3

      = 0 ,     otherwise

then , k=..............

(a) 1/5

(b) 1/4

(c) 1/6

(d) 2/3

 

Answer 1

(c)

x	1	2	3
P(x)	k	2k	3k

Since, the function is a p.m.f.

∴ ∑P(x_i) = 1
∴ k + 2k + 3k = 1
∴ k = 1/6