Answer:
- The marginal gain from Larry's second hour of work is 60 problems
- The marginal gain from Larry's fourth hour of work is 20 problems
- The best combination is 1 hour of working problems + 3 hours of reading
Explanation:
To get the <em><u>marginal gain</u></em> we subtract from the latest hour, in this case the second hour (140), the production from the previous hour (80). 140-80=60. <em>It's always the same, the latest minus the previous one.</em>
So let's do the same for the fourth hour:
Noon................200 problems
minus
11:00 AM..........180 problems
200-180= 20 problems
Now to know how many hours he should spend working on problems and reading, let's compare:
An hour of reading equals to 70 problems made; (because working on 70 problems raises a student’s exam score by about the same amount as reading the textbook for 1 hour).
hours of working problems problems solved
0............................................................0
1.............................................................80
2............................................................140
3............................................................180
hours reading problems equivalent to hours read
4...............................................(4*70)=280
3...............................................(3*70)=210
2...............................................(2*70)=140
1................................................(1*70)=70
finally let's add up the two combinations (0 and 4, 1 and 3, 2 and 2, 3 and 1)
0 and 4_______________0+280= 280
1 and 3________________80+210=290
2 and 2_______________140+140=280
3 and 1________________180+70=250
<em>And the best combination is 1 hour of working problems + 3 hours of reading=</em><em>290</em>
