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Mixture Question

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by Danny@GMATAcademy » Sun Jul 03, 2016 7:13 am
Three gas cans sit in a garage. The first contains a gas-oil mixture that is 95% gas. The second contains a gas-oil mixture that is 75% gas. The third is empty. If a gas-oil mixture that is 80% gas is to be mixed in the empty can by combining some of the original two mixtures, then what ratio of mixture from the first can to mixture from the second can should be added to the third can?

A)1:3
B)1:2
C)1:1
D)2:1
E)3:1
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Source: — Problem Solving |

by 800_or_bust » Sun Jul 03, 2016 9:53 am
Danny@GMATAcademy wrote:Three gas cans sit in a garage. The first contains a gas-oil mixture that is 95% gas. The second contains a gas-oil mixture that is 75% gas. The third is empty. If a gas-oil mixture that is 80% gas is to be mixed in the empty can by combining some of the original two mixtures, then what ratio of mixture from the first can to mixture from the second can should be added to the third can?

A)1:3
B)1:2
C)1:1
D)2:1
E)3:1
.95A + .75B = .80(A + B)
.95A + .75B = .80A + .80B
.15A = .05B
A/B = 1/3 (or A:B = 1:3)

Answer choice: A
800 or bust!
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by OptimusPrep » Wed Jul 06, 2016 7:12 am
Danny@GMATAcademy wrote:Three gas cans sit in a garage. The first contains a gas-oil mixture that is 95% gas. The second contains a gas-oil mixture that is 75% gas. The third is empty. If a gas-oil mixture that is 80% gas is to be mixed in the empty can by combining some of the original two mixtures, then what ratio of mixture from the first can to mixture from the second can should be added to the third can?

A)1:3
B)1:2
C)1:1
D)2:1
E)3:1
Assume the two mixtures are mixed in x:1 ratio

0.95x + 0.75 = 0.8*(x + 1)
0.15x = 0.05
x = 0.05/0.15 = 1/3

Hence ratio = x:1 = (1/3):1 = 1:3

Correct Option: A
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by Matt@VeritasPrep » Thu Jul 07, 2016 3:36 pm
.95x + .75y = .8*(x + y)

.15x = .05y

3x = y

x/y = 1/3
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