how many liters of a 70% acid solution must be mixed with a 15% acid solution to get 385 L of a 60% acid solution?

Question

how many liters of 70% acid solution must be mixed with a 15% acid solution to get 385 L of a 60% acid solution

Answer 1

Hello Andy.

 

Let

S = # liters of 70% acid solution

F = # liters of 15% acid solution

 

S + F = 385

.7S + .15F = 385(.6)

 

Let's multiply the 2nd equation by 100 to get rid of the decimals.

 

S + F = 385

70S + 15F = 385(60)

 

From the first equation S = 385-F.  Substitute this in the second equation.

 

70S + 15F = 385(60)

70(385-F) + 15F = 385(60)

26950 - 70F + 15F = 23100

 

Combining terms and solving for F, we get

3850 = 55F

70 = F

 

Since S = 385-F

S = 385-70 = 315

 

So you will need 315 liters of 70% acid solution and 70 liters of 15% acid solution to make 385 liters of 60% acid solution.