# SOLUTION: A chmistry student needs 10L of a 12% acid solution. The laboratory has an ample amounts of 10% and 20% acid solutions. How many liters of each solution should the student mix?

Algebra ->  Algebra  -> Percentage-and-ratio-word-problems -> SOLUTION: A chmistry student needs 10L of a 12% acid solution. The laboratory has an ample amounts of 10% and 20% acid solutions. How many liters of each solution should the student mix?      Log On

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 Click here to see ALL problems on Percentage-and-ratio-word-problems Question 28406: A chmistry student needs 10L of a 12% acid solution. The laboratory has an ample amounts of 10% and 20% acid solutions. How many liters of each solution should the student mix?Answer by longjonsilver(2297)   (Show Source): You can put this solution on YOUR website!mixture questions are all about BEFORE and AFTER...they have to be equal. Let x=amount of 10% acid to be added. and so how much of the 20% acid? Leap of faith... it is everything else of the 10litres of the final amount surely? so (10-x)litres of the 20% acid. --> 0.10*x + 0.20(10-x) is everything before mixing. After mixing, we have 10 litres of a 12% acid --> 0.12*10 so 0.10*x + 0.20(10-x) = 0.12*10 0.1x + 2 - 0.2x = 1.2 -0.1x + 2 = 1.2 -0.1x = -0.8 x = -0.8/-0.1 x = 8 litres and so we need 8 litres of the 10% acid and 2 litres of the 20% acid. Easy? :-) jon.