Chapter 11.3, Problem 78E

Revenue The monthly sales of Sunny Electronics’ new iSun media player is given by $q\left(t\right)=2,000t-100t^2$ units per month, t months after its introduction. The price Sunny charges is $p\left(t\right)=100-t^2$ dollars per iSun, 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 6 months after the introduction of the iSun. Interpret your answer. [HINT: See Example 4(a).]