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Oil A and Oil B.

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by vk_vinayak » Mon Aug 27, 2012 2:53 am
A certain industrial machine requires 15 quarts (480 ounces) of oil every day, and it is given a mixture of oil A and oil B. Oil A consists of 5% special additives while oil B consists of 8% special additives. If the machine needs exactly 30 ounces of the special additives to ensure smooth operation, then how much of oil A, in ounces, should be in the mixture?

A. 260
B. 280
C. 290
D. 300
E. 320
- VK

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by GaneshMalkar » Mon Aug 27, 2012 3:30 am
vk_vinayak wrote:A certain industrial machine requires 15 quarts (480 ounces) of oil every day, and it is given a mixture of oil A and oil B. Oil A consists of 5% special additives while oil B consists of 8% special additives. If the machine needs exactly 30 ounces of the special additives to ensure smooth operation, then how much of oil A, in ounces, should be in the mixture?

A. 260
B. 280
C. 290
D. 300
E. 320

A question of just trial and error as the values are far apart....

Start with value C which is 290

290 - 5% = 14.5
190(480 - 290) - 8% - 15.2
total = 29.7 which is less than 30 by 0.3

so we need to go less for Oil A

280 - 5% = 14
200 - 8% = 16
total = 30

So the correct answer is 280 for Oil A:)
If you cant explain it simply you dont understand it well enough!!!
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by das.ashmita » Tue Aug 28, 2012 1:53 am
A simpler approach :)

let the amount of A in mixture be x and amount of B be (480-x)
0.05x + 0.08(480-x) = 30
=>x = 280

Hence Ans B
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by everything's eventual » Wed Aug 29, 2012 8:49 am
0.05 A + 0.08 B = 30
A + B = 480

Solve for A and you get A= 280.
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