Textbook Problem

Finding Expected Value, Variance, and Standard Deviation In Exercises 1-12, use the given probability density function over the indicated interval to find the (a) expected value,

(b) variance using the alternative formula, and

(c) standard deviation of the random variable.

(d) Then sketch the graph of the probability density function and locate the mean on the graph. See Examples 1, 2, and 5.

$f(x)=\frac{1}{2}-\frac{1}{8}x,\left[0,4\right]$