Answer:
1 hour working on problems, 3 hours reading
Step-by-step explanation:
the question is not complete:
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 Marginal gain
8:00 AM 0
9:00 AM 80 80
10:00 AM 140 60
11:00 AM 180 40
Noon 200 20
Since Bob's is able to answer more than 70 questions per hours only during one hour (from 8 to 9 AM), he can benefit more from reading the next 3 hours. Reading would be equivalent to answering 210 questions, while Bob was only able to answer 120 more questions in the following 3 hours.