Question

A discrete random variable X has a geometric distribution with mean 3. Calculate P(X=5)

Answer 1

mean = 1/p

-> p = 1/3

P(X=5) = p*(1-p)^(5-1)
P(X=5) = (1/3)*(2/3)^4 = 16/243

Answer 2

Just one quick question.. how did you transfer the mean into a probability?

Answer 3

The mean or expected value of a geometric distribution is 1/p

Answer 4

Ok thanks