SOLUTION: a chemist is mixing a solution that is 2% acid and another solution that is 8% acid. She needs to make 75 mL of a solution that is 5% acid. How much of each solution should she use

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Question 1139269: a chemist is mixing a solution that is 2% acid and another solution that is 8% acid. She needs to make 75 mL of a solution that is 5% acid. How much of each solution should she use?
Found 2 solutions by Alan3354, josgarithmetic:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
a chemist is mixing a solution that is 2% acid and another solution that is 8% acid. She needs to make 75 mL of a solution that is 5% acid. How much of each solution should she use?
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5 is the average of 2 & 8.
---> equal amounts.

Answer by josgarithmetic(39614) About Me  (Show Source):
You can put this solution on YOUR website!
x, amount of the 8% acid
75-x, amount of the 2% acid

Want 75 mL of 5% acid solution --

8x%2B2%2875-x%29=5%2A75
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8x%2B2%2A75-2x=5%2A75
%288-2%29x%2B2%2A75=5%2A75
%288-2%29x=%285-2%29%2A75
x=%28%285-2%29%2A75%29%2F%288-2%29
x=%283%2A75%29%2F6-----------------and do you see that this is HALF the intended volume of the mixture?