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word problem help?, please?
XxchinachicaxX
post Feb 27 2005, 07:16 PM
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Can someone please solve this math problem for me, and perhaps explain how they did it?

Alice's grandfather uses brine solution to make pickles. He has 8 gallons of 5% brine solution (5% salt and 95% water). How much of this solution should be poured and replaced with water to result in a 3% solution?

Hopefully someone will be nice enough to help me...but math sucks so I understand if you don't want to.
 
 
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innovation
post Feb 28 2005, 09:33 AM
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i remember learning something like this in algebra 1.. we made tables and stuff, and it was really clear that way. but unfortunately, i forget how to do that, so i'm going to use my own method, if that's alright.

i'm going to do this in terms of water because that's the substance that you're adding.

the facts

1. finding: amount in gallons to be replaced
2. have: 8 gallons of 95%
3. which means: 0.95 * 8 = 7.6 gal of water
4. but you want: 8 gallons of 97%
5. in other words, you want: 0.97 * 8 = 7.76 gal of water

the solution

the equation would be:

7.76 = 7.6 - 0.95x + 1x

x = number of gallons to replace with water

in other words, the amount of water you want is equal to the amount of water you have, minus 95% of the amount of solution you remove, plus 100% of the amount of solution that you add. after you solve the equation, you find that x = 0.32, so it would be 0.32 gallons.

i'm not really sure of this answer, however; and i know, this explanation was totally confusing. why not ask a teacher?
 

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