Darnell is a hard-working college senior. One Thursday, he decides to work nonstop until he has answered 250 practice problems for his math course. He starts work at 8:00 AM and uses a table to keep track of his progress throughout the day. He notices that as he gets tired, it takes him longer to solve each problem.

Time Total Problems Answered

8:00 am 0

9:00 am 100

10:00 am 175

11:00 225

Noon 250

Use the table to answer the following questions.

The marginal, or additional, benefit from Darnell's second hour of work, from 9:00 AM to 10:00 AM, is __________ problems.

The marginal benefit from Darnell's fourth hour of work, from 11:00 AM to noon, is ___________ problems.

Later, the teaching assistant in Darnell's math course gives him some advice. "Based on past experience," the teaching assistant says, "working on 87.5 problems raises a student's exam score by about the same amount as reading the textbook for 1 hour." For simplicity, assume students always cover the same number of pages during each hour they spend reading.

Given this information, in order to use his 4 hours of study time to get the best exam score possible, how many hours should he have spent working on problems, and how many should he have spent reading?

a. 1 hour working on problems, 3 hours reading

b. 2 hours working on problems, 2 hours reading

c. 3 hours working on problems, 1 hour reading

d. 4 hours working on problems, 0 hours reading