Bob is a hard-working college freshman. One Tuesday, he

Bob is a hard-working college freshman. One Tuesday, he decides to work nonstop until he has answered 200 practice problems for his chemistry 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 80
10:00 AM 140
11:00 AM 180
Noon 200

The marginal, or additional, gain from Bob’s first hour of work, from 8:00 AM to 9:00 AM, is _____ problems.

The marginal gain from Bob’s third hour of work, from 10:00 AM to 11:00 AM, is_____ problems.