Quandaries and Queries


Dear Sir or Madam:

I recently received $7,987.68. This amount consisted of $7,543.61 invested at 6% per annum, compounded daily. I am trying to find out how many days this investment accrued interest.

Thank you,



Hi Bruce,

If you invest $A at an annual interest rate of r per anum, compounded m times a year then the value after t years is $V given by

You have $V = $7987.68, $A = $7543.61, r = 0.06 and m = 365. I substituted the values, divided both sides by A and then took the log of both sides to get

0.02484143 = mt (0.000071385)

and hence

mt = 347.99 days



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