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| Math Central | Quandaries & Queries |
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Question from RON: USING 4 PARTS OF 80% SOLN AND 1 PART OF 20% SOLN, WHAT IS THE % OF THE RESULTING SOLN? FOR 120ML USE 96 ML OF THE 80% SOLN AND 24 ML OF THE 20% SOLN BUT WHAT IS |
Ron,
I agree that the mixture is an 68% solution. My solution doesn't involve the second sentence at all.
First 80% is 0.80 and 20% is 0.20 so one part of a 20% solution contains 1 × 0.20 = 0.20 parts of the dissolved material. Four parts of an 80% solution contains 4 × 0.80 = 3.20 parts of the dissolved material. You have mixed 1 part and 4 parts so you have 1 + 4 = 5 parts of the new mixture. Hence the fraction of the mixture that is made up of the dissolved material is (0.20 + 3.20)/5 = 3.40/5 = 0.68 of 68%.
Penny
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