In Exercises 65 through 68, the demand function q = D(p) for a particular commodity is given in terms of a price p per unit at which all q units can be sold. In each case:

(a) Find the elasticity of demand and determine the values of p for which the demand is elastic, inelastic, and of unit elasticity.

(b) If the price is increased by 2% from $15, what is the approximate effect on demand?

(c) Find the revenue R(p) obtained by selling q units at the unit price p. For what value of p is revenue maximized?

D(p) = 5,000( p + 11)e^−0.1p