fluke wrote:

Of the 9,000 people who voted in a recent election, how many women voted for candidate X?

1) The percentage of women voting for candidate X was twice the percentage of women voting against candidate X.

2) 3000 men voted for candidate X.

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

..........| Men | Women

------------------------------

.... for X | a | b

------------------------------

against X | c | d

=> Q: b = ?

a + b + c + d = 9000

Since we have 4 variables and 1 equation, E could be the answer most likely.

1) & 2)

From the condition 1), we have b = 2d.

From the condition 2), we have a = 3000.

Since we have only 2 equations b = 2d and a = 3000, we can't figure out b and solve this question.

Therefore, the answer is E as expected.

For cases where we need 3 more equations, such as original conditions with “3 variables”, or “4 variables and 1 equation”, or “5 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 80 % chance that E is the answer, while C has 15% chance and A, B or D has 5% chance. Since E is most likely to be the answer using 1) and 2) together according to DS definition. Obviously there may be cases where the answer is A, B, C or D.

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