How many liters of antifreeze that is 18% alc must be mixed with antifreeze that is 10% alc to reduce antifreeze that is 15% alc

Question

I have done so many of these but for some reason I cant figure a couple out, please help.

Answer 1

This problem is one in which a more concentrated solution will be diluted, and it can be solved by using the formula

 

C1 x V1 + C2 x V2 = C3 x V3, where C = Concentration and V = Volume

 

We have the Concentration information, namely a solution of 18% which will be diluted with a solution of 10% to produce a solution of 15%.

 

in the absence of any volume data, we can only write a general formula

 

Let x  = V1, then 18%x + 10%(V3 - x) = 15%V3

If we convert the % figures to decimals, we get

0.18x + 0.1(V3 - x) = 0.15V3

 

You can solve the equation by assuming any volume of V3.