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Antifreeze Problem

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Antifreeze Problem

by charlie33 » Sat Jun 27, 2009 8:01 am
How much pure antifreeze must be added to 12 gallons of 10% antifreeze to make a 40% antifreeze solution?

A. 9 gallons
B. 12 gallons
C. 3 gallons
D. 6 gallons
E. 4.8 gallons
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by truplayer256 » Sat Jun 27, 2009 8:08 am
12 gallons- 10% antifreeze

12(1/10)=1.2 gallons antifreeze

x= amount of pure antifreeze added

1.2+x/12+x=2/5

6+5x=24+2x

18=3x

x=6 gallons of pure antifreeze must be added in order to make a 40% antifreeze solution.

D
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Re: Antifreeze Problem

by ssmiles08 » Sat Jun 27, 2009 8:11 am
IMO D.

10% of 12 gallons are 1.2 of existing antifreeze solution.

we are adding x amounts of antifreeze.

total solution is 40% antifreeze: 0.40(12 + x)

1.2 + x = 0.40(12 + x) and solve for x.

x = 6.
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by ghacker » Sat Jun 27, 2009 10:57 am
No calculations needed

They have given the answer choices

The Answer is 6

(When one adds pure G the total amount and the amount of G increases )
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