Question

How many gallons of a 20% acid solution should be mixed with 30 gallons of a 40% solution, to obtain a mixture of 30% acid solution.

Answer 1

30 gallons of 20% acid solution should be mixed.

Explanation:

Let x gallons of a 20% acid solution was mixed with 30 gallons of a 40% solution, to obtain a mixture of 30% acid solution.

Therefore, final volume of the solution will be (x + 30) gallons.

Now concept to solve this question is

20%.(x) + 40%.(30) = 30%.(x + 30)

0.20(x) + 0.40(30) = 0.30(x + 30)

0.20x + 12 = 0.30x + 9

0.30x - 0.20x = 12 - 9

.10x = 3

x =
`(3)/(0.1)`

x = 30 gallons

Therefore, 30 gallons of the 20% acid solution should be mixed.