Chapter 4.3, Problem 77E

Revenue The monthly sales of Sunny Electronics’ new sound system are given by $q\left(t\right)=2,000t-100t^2$ units per month, t months after its introduction. The price Sunny charges is $p\left(t\right)=1,000-t^2$ dollars per sound system, t months after introduction. Find the rate of change of monthly sales, the rate of change of the price, and the rate of change of monthly revenue 5 months after the introduction of the sound system. Interpret your answer. [HINT: See Example 4(a).]