Bunuel
Competition Mode Question
An article purchased by Mr. A for $x and was sold to Mr. B for $y. What was Mr. A's profit percentage?
(1) Mr. B's cost price was $20 more than Mr. A's cost price
(2) Had Mr. A sold the article for double the price than he actually sold it for, his profit would have been 600% more than his actual profit
Are You Up For the Challenge: 700 Level QuestionsForget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
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https://www.mathrevolution.com/gmat/lesson for details.
The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question. We should simplify conditions if necessary.
The question asks the value of \([m]y-x/x\)\cdot100[/m].
When a question asks for a ratio, if one condition includes a ratio and the other condition just gives a number, the condition including the ratio is most likely to be sufficient. This tells us that B is most likely to be the answer to this question.
Thus we need to check condition 2) first which is ratio.
Condition 2)
We have \(2y - x = 7(y-x)\) or \(6x = 5y\).
Thus we have \(\frac{y}{x} = \frac{6}{5}\).
Then we have \(\frac{y-x}{x} \cdot 100 = (\frac{y}{x}-1) \cdot 100 = (\frac{6}{5}-1) \cdot 100 = 20\).
Condition 1)
We have \(y=x+20\).
Then \(\frac{y-x}{x} \cdot 200 = \frac{20}{x} \cdot 100\).
Since we don't know the value of x, condition 1) is not sufficient.
Therefore, B is the answer.
If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.