Math word probelm

Question

pure acid is to be added to a 5% acid solution to obtain 95L of 60% solution what amount of each solution should be used?

 

how many lit of 100% pure acid should be used to make the solution 

Answer 1

Let x = the amt of 5% acid. The amount of pure acid will be (95 - x) because the total mixture is 95 L. That gives us the following formula expressing the concentration of each solution in relation to the mixture:

 

.05x + (95 - x) = .60 (95) Multiply thru by 100.

5x + 100(95 - x) = 5700

5x + 9500 - 100x = 5700

-95x = -3800

x = 40 L of 5% acid. So, the amount of pure acid is 95 - 40 = 55 L.