Math Is Fun Forum

frem

Member

Registered: 2008-02-23

Posts: 3

anybody please help me!!!

Please help me to solve the below modelling differential equation question:
A large tank is filled to capacity with 500 gallons of pure water. Brine containing 2 pounds of salt per gallon is pumped into the tank at a rate 0f 5 gal/min. The well mixed solution is pumped out at the rate of 10 gal/min. When is the tank empty?

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: anybody please help me!!!

This isn't really a differential equations question. At least, it doesn't have to be.
The important bits of the question are that the tank initially has 500 gallons of water in it, and that it drains by 5 gallons per minute (because 5 gallons get added and 10 get drained).

Therefore, the tank will be empty after 500/5 = 100 minutes.
The brine part of the question is irrelevant, unless there are more parts to it.

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Why did the vector cross the road?
It wanted to be normal.