Question 728803: If $7,000 is placed in an account with an annual interest rate of 4%, how long will it take the amount to quadruple if the interest is compounded annually? Round your answer to two decimal places.
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
^{nt})
Where  is the future value,  is the present value, i.e. the starting principal,  is the interest rate as a decimal (the percentage divided by 100),  is the number of compounding periods per year, and  is the number of years. Since you are compounding annually,  and the formula reduces to:
^t)
Since you want the principal to quadruple,  must be true, hence solve:
^t\ =\ 4)
for
Hint: Take the log of both sides, any base -- it doesn't matter. Then use: \ =\ a\log_b(x))
John
Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
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