If average fixed costs equal $60 and average total costs equal $120 when output is 100, the total variable cost must be:

The model of aggregate demand and aggregate supply explains the relationship between

a. the price and quantity of a particular good. b. unemployment and output. c. wages and employment. d. real GDP and the price level.

Electric companies generally practice price discrimination and charge higher prices for electricity used for illumination and lower prices for electricity used for heat. These lower prices for electric heating result primarily from:

A. The existence of good heating substitutes B. Economies of scale in electric heat generation C. Prices for electric heat being set at the socially optimal level D. Strict government regulation of the price charged for electric heat