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Mon 22 Aug, 2005 06:40 pm
There are 12 liters of a mixture of acetone in alcohol that
is 33 and 1/3% acetone. How many liters of alcohol must be
added to the mixture to reduce it to a mixture containing
25% acetone.
I tried to set up a proportion but did not even come close.
The correct answer is 4 but how do I find it?
ok
1/3 (12) = 1/4(x)
4 = 1/4x
4 divided by 1/4 = x
16 = x but the answer is 4.
I don't how to use your hint to find the correct answer: 4.
The "x=16" you obtained is the total volume of the mixture with 25% acetone. Since you started with 12 L of mixture, that means you added 16 - 12 = 4 L of alcohol to dilute the composition from 33.3% to 25% acetone. So, the answer to the question "How much alcohol must be added" is 4. (You were almost there--just missed the last step)
It would have been complete if I had put:
1/3 of 12 is 1/4 of (12+ ?)
ok
I totally get it now. Thank you for your tips.
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