Intermediate Microeconomics and Its Application 12th Edition by Walter Nicholson,Christopher Snyder

Exercise 14

Late Bloomer is taking a course in microeconomics. Grading in the course is based on 10 weekly quizzes, each with a 100-point maximum. On the first quiz, Late Bloomer receives a 10. In each succeeding week, he raises his score by 10 points, scoring a 100 on the final quiz of the year.
a. Calculate Late Bloomer's quiz average for each week of the semester. Why, after the first week, is his average always lower than his current week's quiz?
b. To help Late Bloomer, his kindly professor has decided to add 40 points to the total of his quiz scores before computing the average. Recompute Late Bloomer's weekly averages given this professorial gift.
c. Explain why Late Bloomer's weekly quiz averages now have a U-shape. What is his lowest average during the term?
d. Explain the relevance of this problem to the construction of cost curves. Why does the presence of a "fixed cost of 40 points result in a U-shaped curve? Are Late Bloomer s average and marginal test scores equal at his minimum average?