SOLUTION: An investment offers to quadruple your money in 15 months (don't believe it). What rate per three months are you being offered? I got 21.25% Could you show me where I went wrong

Question 910817: An investment offers to quadruple your money in 15 months (don't believe it).
What rate per three months are you being offered? I got 21.25% Could you show me where I went wrong please?
Answer by LinnW(1048) (Show Source): You can put this solution on YOUR website!
Let x = the percent increase every 3 months
1(1+x)^5 = 2 , The original amount 1 compounded at x percent for 5 periods of
3 months each
Plugging the above into a solver like www.wolframalpha.com
the result is x is approximately 0.148698
Testing 1.148698^5 we get 1.9999969... so we are pretty close.

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