Question

A storage tank is completely empty. At 12:00 noon, oil is poured into the top of the tank and a valve is opened at the bottom. Oil is poured into the tank at a rate of 2.1 gallons per minute and the valve at the bottom empties at a rate of 1.9 gallons per minute. If the tank does not fill until 12:00 the next day, how many gallons does the tank hold?

Answer 1

Answer: We can start by using the concept of rates.

At 12:00 noon, oil is poured into the top of the tank at a rate of 2.1 gallons per minute and the valve at the bottom empties at a rate of 1.9 gallons per minute.

As the tank is empty at the beginning, the rate at which the oil is poured into the tank is equal to the rate at which the oil is leaving the tank.

2.1 gallons per minute - 1.9 gallons per minute = 0.2 gallons per minute

As the tank does not fill until 12:00 the next day, the difference between the rate of oil that enters the tank and the rate of oil that leaves the tank is equal to zero over the time frame.

0.2 gallons per minute * 1440 minutes = 288 gallons

So, the tank holds 288 gallons.

Explanation: