blockman wrote:

Jackie has two solutions that are 2 percent sulfuric acid and 12 percent sulfuric acid by volume, respectively. If these solutions are mixed in appropriate quantities to produce 60 liters of a solution that is 5 percent sulfuric acid, approximately how many liters of the 2 percent solution will be required?

A) 18

B) 20

C) 24

D) 36

E) 42

Using the Scale Method (Easiest for Me)

2%------------------------------------------12%

^

7

If there were equal parts of 2% and 12% solution, the average would be 7% [(2+12)/2]. With a split of 30 liters for each solution to create 60 liters

The question stem stated that when the solutions are mixed, 60 liters will have a

concentration of 5%This means we need more than 30 liters of the 2% solution. So we can cross of A, B, C.

2%------------------------------------------12%

(5-2)=3 ^ (12-5)=7

5%

Ratio is 3x:7x = 10x

If we know there's 60 Liters, then x in 10x will equal to 6

3*6 =18 liters for the 12% solution

7*6 = 42 liters for the 2% solution

Answer is E