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