Microeconomics 6th Edition by Robert Hall, Shirley Kuiper, Marc Lieberman

Exercise 6

In Table 1,when output rises from 90 to 130 units,marginal cost is $3.00. For this change in output,marginal cost is greater than the previous AVC ($2.67)but less than the previous ATC ($4.33). According to the relationship between marginals and averages you learned in this chapter:
Table 1 Short-Run Costs for Spotless Car Wash

a. What should happen to AVC due to this change in output? Does it happen?
b. What should happen to ATC due to this change in output? Does it happen?