Peter R. answered 05/05/22
Adjunct Lecturer - Math Department - Borough of Manhattan C.C.
Take the first derivative of the function and set it = 0 to find price for max. profit. (slope of revenue function = 0)
f'(R) = 2(-2.5)p + 650 = 0 -> -5p = -650 -> p = $130 to maximixe revenue.
Rev @ $130 is -2.5(130)2 + 650(130) = -42250 + 84500 = $42,250.
As a check, revenue at p = $120 and $140 is $42,000 for both, so $130 is the price for max. revenue.