The Life of a Battery Is a Random Variable with Probability

Short Answer

The life of a battery is a random variable with probability density function $f ( x ) = \frac { 3 } { 56 } x ^ { 2 }$ , $2 \leq x \leq 4$ where x is the time in months. Calculate E(X).
Enter just a reduced fraction of form $\frac { a } { b }$ unlabeled.