Sum of money

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by GMATGuruNY » Tue Mar 24, 2015 7:23 am
The posted problem is ambiguously worded.
It seems to be asking the following:
In 16 years, an investment earning x% simple annual interest triples in value. How many years does it take the investment to double in value?

A)7 years
B)8 years
C)8.5 years
D)9 years
Since the investment takes 16 years to triple in value, it takes 16 years to earn 200% in interest.
We must determine how many years are required for the investment to earn 100% in interest, with the result that the investment doubles in value.
Set up the following proportion:

(200 percent)/(16 years) = (100 percent)/(x years)
200x = 1600
x = 8 years.

The correct answer is B.
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by ceilidh.erickson » Sat Mar 28, 2015 4:16 pm
You should avoid studying from sources that are ambiguously worded and un-GMAT-like.
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EdM in Mind, Brain, and Education
Harvard Graduate School of Education