GRE Math Review Questions

Category - GRE Math

How long will it take for Ron’s $37,353 investment to double if he expects 9% returns?
  1. 5 years
  2. 8 years
  3. 9 years
  4. 9.5 years
  5. 10 years
Explanation
Answer: D - To calculate this answer mentally, use the Rule of 72.

Divide 72 by the rate of growth. In this example, Ron’s money would double in 8 years (72/9). The rule of 72 is a quick mental calculation tool that provides an estimate of how long it would take an investment to grow double.


Key Takeaway: For a few days, practice this every time you see a growth rate in the news paper or at work.
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