SOLUTION: If you put $1000 into a savings account that bears 1.5% interest per year, how long will it take that money to quadruple?

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Question 1099037: If you put $1000 into a savings account that bears 1.5% interest per
year, how long will it take that money to quadruple?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
quadruple is $4000
4000=1000(1+.015)^n
4=1.015^n
ln4=n1n (1.015)
n=93.1 years
rule of 72: doubling time is 72/interest rate=48 years
quadrupling is doubling of doubling, and that would be two doublings or 96 years, a good approximation.