This GMAT Sample Math question is a GMAT 550-600 level arithmetic problem solving question from the topic percentages and fraction. The concept tested is to find how much % more or % less is quantity A compared to quantity B.

Question 6: Robin earns 30% more than Erica. Charles earns 60% more than Erica. How much % is the wages earned by Charles more than that earned by Robin?

1. 23%
2. 18.75%
3. 30%
4. 50%
5. 100%

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Video Explanation

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Explanatory Answer | GMAT Percentage Q6

The key idea behind solving this percents question lies in understanding how to compare percentages and figuring out by what percentage is one higher or lower than the other.
All data in this question is given in percent terms. So, let us assign something to be 100.
Robin’s earnings and Charles’ earnings are expressed in terms of Erica’s. So, let us assume Erica’s wages to be $100.

Robin earns 30% more than Erica. So, Robin's wages = 100 + 30% of 100 = $130
Charles earns 60% more than Erica. So, Charles's wages = 100 + 60% of 100 = $160
Charles earns $30 more than Robin who earns $130.
The difference between their wages is $30.

What base do we use - Earnings of Charles or that of Robin?

Wages of Charles has been compared with that of Robin. The question is asking us to express how much more did Charles earn compared with Robin. So, Robin’s wages will be our base.
\\frac{\text{Difference}}{\text{Base}}) = \\frac{30}{130}) × 100 = 23.07%
Charles earns 23.07% more than Robin.

Choice A is the correct answer.