Pmf of the amount of memory

Question

The pmf of the amount of memory X (GB) in a purchased flash drive is given as the following.

x	1	2	4	8	16
p(x)	0.05	0.10	0.30	0.45	0.10

(a) Compute E(X). (Enter your answer to two decimal places.)

GB

(b) Compute V(X) directly from the definition. (Enter your answer to four decimal places.)

GB²

(c) Compute the standard deviation of X. (Round your answer to three decimal places.)

GB

(d) Compute V(X) using the shortcut formula. (Enter your answer to four decimal places.)

GB²