A Hardware Store Will Cut Lumber Any Length Between 5 $f ( x ) = \frac { 1 } { 15 }$

Short Answer

A hardware store will cut lumber any length between 5 and 20 feet. Say X is the length of lumber requested by a customer. Then X is a uniform random variable with probability density function $f ( x ) = \frac { 1 } { 15 }$ Find E(X) and Var(X).
Enter just two reduced fractions (unlabeled) in the order E(X), Var(X) separated by a comma.