Re: Mixture story problem

Quote:

Originally Posted by

**Kibbygirl** Trying to learn how to do these types of problems. The last one I had for homework was wrong.

How much 12% Na_{2}SO_{4} and pure water must be mixed to produce 22.8 gallons of a mixture that is 7% sodium sulfate?

I started with: Let x = the # of gallons of 12% Na_{2}SO_{4 }

And Let y = the # of gallons of 100% water

...

1. Using your labeling you already know:

$\displaystyle \left|\begin{array}{rcl}x+y&=&22.8 \\ 0.12x&=& 0.07(x+y) \end{array} \right.$

2. Solve for x and y. I've got $\displaystyle (x,y) = (13.3, 9.5)$

Re: Mixture story problem

Code:

`a @ x`

b @ y

========

a+b @ z

z = (ax + by) /(a+b)

a @ 12

22.8-a @ 0

===========

22.8 @ 5

5 = (12a + 0) / 22.8

a = 13.3