This is a fairly easy question on ratios, but with a big trap in terms of language. The most common answer that a lot of students get on this question is 60 i.e. option D. However, this is the trap answer.
Questions like these on ratios test your knowledge of mutliples of numbers. As such, although the conventional approach of assuming the stamps as 5x and 3x and then building an equation followed by solving the equation yields you the answer, it’s always good to approach ratio questions using numbers.
We know that the number of stamps that Kaye and Alberto had are multiples of 5 and 3 respectively. So, what do we do? Do we start with 5 and 3? The answer is a bigg no. Observe the options, all the options are bigger numbers than 5 and 3. And remember that we are trying to find the difference between the number of stamps. We need to take bigger multiples of 5 and 3, which are multiples of 10 as well (preferably).
Let’s try 50 and 30, then. After gifting 10 stamps to Alberto, the respective numbers with Kaye and Alberto would be 40 and 40. This is not in the ratio of 7:5. So, 50 and 30 are not the number of stamps.
If we try 100 and 60, we obtain the numbers 90 and 70 after the gifting process. This is in the ratio of 9:7, NOT 7:5.
When we try 150 and 90, we see that the resultant numbers after Kaye gifts alberto would be 140 and 100 which are in the ratio of 7:5. Therefore, Kaye must have started off with 150 stamps and Alberto with 90 stamps. So, Kaye had 60 more stamps than Alberto?? No, that’s not correct.
Observe that
the question mentions “As a result of the gift…”. This means, we need to find out
how much more Kaye had AFTER gifting 10 stamps to Alberto. AFTER gifting 10 stamps to Alberto, Kaye had 140 and Alberto had 100, so Kaye had 40 more stamps.
The correct answer option is C.Every word, every phrase and every sentence in a GMAT question is valuable. If you rush through the questions without paying due attention, you run the risk of falling for the trap answers. If required,
after you compute an answer, re-read the question statement and satisfy yourselves that you have indeed answered the actual question and NOT what you thought the question was.Hope that helps!
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