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# I need help with a simple math question

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Intern
Joined: 21 Jun 2008
Posts: 4
I need help with a simple math question [#permalink]

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18 Feb 2009, 07:21
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

I am having difficulty with the following question and do have the answer, but am uncertain as how to arrive there:

There are x gallons of 1% milk, y gallons of 2% milk, and z gallons of 3% milk. If one created the combination of x+y+Z to yield 1.5% milk, what's x in terms of y and z?

The answer happens to be y+3z

Could someone please help me in terms of the steps to get this answer (it seems simple, but I am having a mind block).

THANKS!
Senior Manager
Joined: 08 Jan 2009
Posts: 327
Re: I need help with a simple math question [#permalink]

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18 Feb 2009, 07:53
0.01x+0.02y+0.03z = 0.015( x + y + z)

Assume y = 40 and x =60

0.01x+ 0.8 +1.8 = .015( x+ 100)

simplifying this X = 220.

When u subsititute y and z in the eqn x= y+3z =220.
Manager
Joined: 17 Dec 2008
Posts: 173
Re: I need help with a simple math question [#permalink]

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18 Feb 2009, 08:01
Similar eqn. but don't substitute numbers here(else you need to evaluate all 5 answers).
(x + 2y + 3z) /100 = 1.5(x+y+z)/100
=> x + 2y + 3z = 1.5(x+y+z)
=> 2x + 4y + 6z = 3x+3y+3z (both sides x 2)
=> 4y + 6z -3y -3z = x
=> x = y + 3z
Re: I need help with a simple math question   [#permalink] 18 Feb 2009, 08:01
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# I need help with a simple math question

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