The GMAT Sample Math question is an arithmetic problem solving question from the topic percentages and fraction. The concept tested is finding out % increase and % decrease from a base value.
The difference between the value of a number increased by 12.5% and the value of the original number decreased by 25% is 30. What is the original number?
The correct choice is (B) and the correct answer is 80.
Let the original number be x.
Let A be the value obtained when x is increased by 12.5%.
Therefore, A = x + 12.5% of x
Let B be the value obtained when x is decreased by 25%.
Therefore, B = x - 25% of x
The question states that A - B = 30
i.e., x + 12.5% of x - (x - 25% of x) = 30
x + 12.5% of x - x + 25% of x = 30
37.5% of x = 30
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