Question

Jada walks up to a tank of water that can hold up to 10 gallons. When it is active, a drain empties water from the tank at a constant rate. When Jada first sees the tank, it contains 7 gallons of

water. Three minutes later, the tank contains 5 gallons of water
How many more minutes will it take for the tank to drain completely?

Answer 1

1) Gallons per minute change is -2/3 gallons per minute since it decreases by 2 gallons in 3 minutes

2) we have 5 gallons and lose 2/3 gallons per minute

(2/3 gal/minute)(x minutes) = 5 gallons
x = 5(3/2) = 15/2 = 7.5 minutes to drain the other 5 gallons

3) There was 10 gallons when the tank is full
That is 3 gallons more than the 7 gals there when Jada arrived.
(2/3)(x) = 3
x = 3(3/2) = 9/2 = 4 1/2 minutes

The tank was full 4 1/2 minutes before Jada arrived