Janet is a hard-working college sophomore. One Thursday, she decides to work nonstop until her economics course. She starts work at 8:00 AM and uses a table to keep track of her progress throughout the day. She notices that as she gets tired, it takes her longer to solve each problem.
Time
Total Problems Answered
8:00 AM
105
9:00 AM
135
10:00 AM
150
11:00 AM
165
Noon
180
Use the table to answer the following questions:
1. The marginal, or additional, gain from Janet's second hour of work, from 9:00 AM to 10:00 AM, is 30 problems.
2. The marginal gain from Janet's fourth hour of work, from 11:00 AM to noon, is 15 problems.
Later, the teaching assistant in Janet's economics course gives her some advice. Based on past experience, the teaching assistant says that working on 22.5 problems raises a student's exam score by about the same amount as reading the textbook for an 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 her hours of study time to get the best exam score possible, Janet should have spent 4 hours working on problems and 2 hours reading.