Chapter 3, Problem 34E

The net contents in ounces of canned soup is a random variable with probability distribution

$f\left(x\right)=\{\begin{array}{cc}4\left(x-11.75\right)& 11.75\le x\le 12.25\\ 4\left(12.75-x\right)& 12.25\le x\le 12.75\end{array}$

Find the probability that a can contains less than 12 ounces of product.