Problem:
Steve's empty swimming pool will hold 24,000 gallons of water when full. It will be filled by 4 hoses, each of which supplies 2.5 gallons of water per minute. How many hours will it take to fill Steve's pool?
Answer Choices:
A. 40
B. 42
C. 44
D. 46
E. 48
Solution:
Together the hoses supply 10 gallons per minute to the pool. The pool holds 24,000 gallons, so it will take a total of 10 gallons/minute24000 gallons​=2400 minutes. Because 2400 minutes equals 40 hours, it takes 40 hours to fill Steve's pool.
OR
The hoses supply (10 gallons/minute)(60 minutes/hour)=600 gallons/hour. So it will take 600 gallons/hour24000 gallons​=40 hours to fill Steve's pool.
Answer: A​.
The problems on this page are the property of the MAA's American Mathematics Competitions