Suppose a market has the demand function Q^d=20-0.5P. Using the midpoint method, what is the price elasticity of demand between $30 and $40?

Midpoint Method

A method employed in economics for determining demand or supply elasticity through calculating the mean of the initial and final prices and quantities.

Price Elasticity

A measure of how much the quantity demanded or supplied of a good or service changes in response to a change in its price.