% Mixture Problem

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chipbmk
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Topic: % Mixture Problem
PostWed Nov 18, 2009 1:34 pm
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A contractor combined x tons of gravel mix that contained 10% gravel G by weight, with y tons of a mixture that contained 2% gravel G by weight to produce z tons of a mixture that was 5% gravel G by weight. What is the value of x?

1) y = 10
2) z = 16

OA: D

I do not understand how the OA is correct ...
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palvarez
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PostWed Nov 18, 2009 3:56 pm
Guys, master this type of problems. Learn allegation rule found in books.google.com. Allegation rule is a figurative way of solving algebraically.

Sort the mixtures: 2 and 10

2 ------- 10

------5-----
(10-5) : (5-2) = 5:3

-----------------------------------------------------------------------

Mixture of 2% and 10% = 5%

The ratio of quantities gotta be: 5:3 = y : x

x+y = z

(1) y = 10; x = 6 Sufficient
(2) z = 16; x = 3(2) = 6 Sufficient
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chipbmk
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PostWed Nov 18, 2009 4:30 pm
palvarez wrote:
Guys, master this type of problems. Learn allegation rule found in books.google.com. Allegation rule is a figurative way of solving algebraically.
A link would be cool. I can't seem to find what you are referring to.

Thanks for the help though.
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palvarez
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PostWed Nov 18, 2009 4:36 pm
http://books.google.com/books?id=BoBCOYuOlzkC&pg=PA290&dq=%22alligation+rule%22&ei=UoQES8ecJpDqkQTFqPW_Cg#v=onepage&q=%22alligation%20rule%22&f=false
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Willy
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PostFri Nov 20, 2009 5:26 pm
cant find this book in my bookstore...any other place
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palvarez
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PostSat Nov 21, 2009 1:59 am
Don't waste your money on buying books. Think of that problem as a weight balance problem in physics: another way of loking at the issue.

Average is equilibrium.

Weight*length = constant

w1*l1 = w2*l2

l1 = 5 -2 =3
l2 = 10 -5 = 5

3*y = 5*x

x: y = 3:5

Alligation rule is used heavily in pharmacy classes. Esp it is handy when one is dealing with a mixture of three components, etc.
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