In a certain solution consisting of only two chemicals, for every 3 mi

Initial ratio of A : B = 3 : 7.
10mL of C added

1 - Before C, solution = 50mL, thus A & B can be known and ratio of A, B and C can be known
2 - After C, solution = 60 mL thus before C solution = 50 mL once again A, B and C can be known

Ans. D

P.S. This question tested my reading skills more than my DS skills...

Official answer from Manhattan Prep.

To determine the ratio of Chemical A to Chemical C, we need to find the amount of each in the solution. The question stem already tells us that there are 10 milliliters of Chemical C in the final solution. We also know that the original solution consists of only Chemicals A and B in the ratio of 3 to 7. Thus, we simply need the original volume of the solution to determine the amount of Chemical A contained in it.

(1) SUFFICIENT: This tells us that original solution was 50 milliliters. Thus, there must have been 15 milliliters of Chemical A (to 35 milliliters of Chemical B). The ratio of A to C is 15 to 10 (or 3 to 2).

(2) SUFFICIENT: This tells us that the final solution was 60 milliliters. We know that this includes 10 milliliters of Chemical C. This means the original solution contained 50 milliliters. Thus, there must have been 15 milliliters of Chemical A (to 35 milliliter of Chemical B). The ratio of A to C is 15 to 10 (or 3 to 2).

The correct answer is D.

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