Suppose there's an appliance store that sells refrigerators. It could set its price high and sell very few refrigerators, or it could set its price low and sell many more refrigerators. The following table shows some possible choices this store could make:

The graph below plots the firm's total revenue curve: that is, the relationship between quantity and total revenue given by the two right columns in the table above. The five choices are also labeled. Finally, two black lines are shown; these lines are tangent to the green curve at points B and D.

Using the information on the slope of the lines tangent to the curve at points B and D, plot the slope of the total revenue curve on the graph below. (As it turns out, it's a straight line, so the two points you plot will determine a line.)

The total revenue curve reaches its maximum at a quantity of __ refrigerators per year. At this point, the slope of the total revenue curve is ______________________.

A B D E Price (Dollars per refrigerator) 200 150 100 50 0 Quantity (Refrigerators per year) 0 200 400 600 800 Total Revenue (P x Q) (Dollars per year) 0 30,000 40,000 30,000 0 TOTAL REVENUE (Thousands of dollars per year) 50 45 40 35 30 25 20 15 10 5 0 0 A BA AD 100 200 300 400 500 600 QUANTITY (Refrigerators per year) + 700 E 800 REVENUE (Dollars per refrigerator) 125 100 75 50 25 0 225 -50 -75 -100 4 -125 Ho 100 200 300 400 500 600 QUANTITY (Refrigerators per year) 700 800 Slope of TR