Question

A skating rink manager finds that revenue R based on an hourly fee F for skating is represented by the function R= -480(F - 3.25)^2 + 5070. What hourly fee will produce maximum revenue?

Answer 1

Since you have no calculus (the easy way), lets do it this way. Obviously, it is a parabola going up, then down. So look for the half way point between both x intercepts.
So find the x intercepts.

0=-480(F-3.25)^2 + 5270

F^2+6.5F+3.25^2-5070/480=0 check that, then put it in the form
af^2 + bF+ C=0 and either factor it, or use the quadratic equation.

Then finally, take the average of the two roots, and you have the point of max revenue.