Chapter 11, Problem 13CPS

C. Practical Applications.

For each of the following, set up either a system of equations in two variables or a quadratic equation and solve. (Round to two decimal places if necessary.)

Construction According to Doyle’s log rule, the volume V (in board feet) produced from a log of length L (in feet) and diameter D (in inches) can be estimated by the formula

$V\text{}=\frac{L(D^2-8D+16)}{16}$

What diameter log of length 20 ft will produce 90 board feet of lumber?