그들의 경제학

마법 물약 회사에서 일하면서 의사결정을 해야 하는 해리포터와 친구들 ...
양키들의 교과서 센스란 이렇군요 :

6. Three managers of the Magic Potion Company are discussing a possible increase in production. Each suggests a way to make this decision.

HARRY: We should examine whether our company’s productivity—gallons of
potion per worker—would rise or fall.
RON: We should examine whether our average cost—cost per worker—would rise or fall.
HERMIONE: We should examine whether the extra revenue from selling the additional potion
would be greater or smaller than the extra costs.

Who do you think is right? Why?

* 참고로 Principle of Economics를 읽다가 나온 응용문제 한 꼭지임.