Question: The quantity, q, of a certain skateboard sold depends on the selling price, p. in dollars, so we write q = f(p). You are given that f(140) = 15,000 and f’(140) = -100.

a) What do f(140) = 15,000 and f’(140) = -100 tell you about the sales of skateboards?

b) The total revenue, R, earned by the sale of skateboards is given by R = pq.

Find \[\frac{dR}{dp}\left| _{p=140} \right.\]

c) What is the sign of \[\frac{dR}{dp}\left| _{p=140} \right.\] ? If the skateboards are currently selling for $140, what happens to revenue if the price is increased to $141?