In the figure above, when the price falls from $5 to $4, the price elasticity of demand is

The systematic differences between the control and treatment groups can be controlled by taking two years data, _____.?

A. ?one treatment group before policy change and one after the change B. ?one before the policy change and one after the change C. one control group and one treatment group D. ?one control group before policy change and one after the change

Under a policy of average-cost pricing, a monopolist must charge the price at which its ________ cost curve intersects its ________ curve.

A. marginal; demand B. average variable; demand C. marginal; marginal revenue D. average; demand