Q9 of 40 Page 92

A chemist has two solutions of hydrochloric acid in stock. One is 50% solution and the other is 80% solution. How much of each should be used to obtain 100ml of a 68% solution.

Let the proportion of the first solution be represented by x and the second solution be represented by y.

First solution contains 50% solution =


Second solution contains 80% solution =


Given that together they can give 100ml of 68% solution.




5x + 8y = 680 …I


Total percentage of solution concentration is 100%


x + y = 100 …II


Multiplying Eq. II by 5 and solving with Eq. I


5x + 8y = 680


5x + 5y = 500


-__- -____


3y = 180


y = 60


substitute in Eq. II


x + 60 = 100


x = 40


Hence, the solutions are 40 and 20ml


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