Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE PS – Jackie has two solutions that are 2 percent sulfuric acid and…

Jackie has two solutions that are 2 percent sulfuric acid and…

Solution:

We can begin by defining two variables:

x = the number of liters of 2 percent solution

y = the number of liters of 12 percent solution

x + y = the total number of liters of the resulting solution

Since we are given that the 2 percent sulfuric acid solution and 12 percent sulfuric solution create a mixture with 5 percent sulfuric acid we can create the following equation.

0.02x + 0.12y = 0.05(x + y)

2x + 12y = 5x + 5y

7y = 3x

We also given that the total solution is 60 liters. Thus, we can create the following equation:

x + y = 60 or 7x + 7y = 420.

Since 7y = 3x, we can substitute 3x for 7y in the equation 7x + 7y = 420. Thus, we have:

7x + 3x = 420

10x = 420

x = 42

Answer: E 

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