If the quantity demanded of a product rose from 900 to 1,200 when the price of the product fell from $11 to $9, the price elasticity of demand coefficient is equal to

When demand is unit elastic, a change in price causes total revenue to stay the same because

A) the change in profit is offset by the change in production cost. B) buyers are buying the same quantity. C) total revenue never changes with price changes. D) the percentage change in quantity demanded exactly offsets the percentage change in price.

At any point where a monopolist's marginal revenue is positive, the downward-sloping straight-line demand curve is:

a. perfectly elastic. b. elastic, but not perfectly elastic. c. unit elastic. d. inelastic.