# Mixing problems

1. May 31, 2005

### TheLaughingMan

Can anyone help me out with mixing solution problems, I know its not that hard I just am having trouble understanding what to do. Sometimes its X sometimes its X/volume of the tank. Can anyone explain it to me in a simple way?

2. Jun 1, 2005

### john_in_pdx

If you give us a sample problem maybe we could help break it donw for you?

3. Jun 1, 2005

### TheLaughingMan

Sample:
A swimming pool whose volume is 10,000 gal contains water that is .01% chlorine. Starting at t=0, city water containing .001% Cl is pumped in at 5 gal/min. The pool water flows out at the same rate. What is the % of chlorine in the pool after 1 hr? When will the pool be .002% Cl ?

4. Jun 1, 2005

### Pyrrhus

Can you post an attempt?, it'll figure out what you are not understanding.

5. Jun 29, 2005

### mathmike

it seems you dont know how to set up the prob. you need to find y(60).
to do this you let y(t)=the amount of cl in the pool at time t. you need to find an expression for dy/dt.

dy/dt = rate in - rate out

rate in =5 gal / min * .001%

rate out = y(t) / 10000 * 5 gal / min

so dy /dt = (5 gal/min * .001%) - (y(t) / 10000 * 5 gal/ min)

you then find the I.F. and intergrate

6. Jun 29, 2005