An annuity written as a geometric series has r equal to 1.005 . determine the annual interest rate for the annuity if the interest is compounded monthly

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The formula to be used for this problem is

r^n = 1 + i, where i is the annual interest rate

Since the interest rate is compounded monthly, he would make 12 annuities in a year. Thus,

1.005^12 = 1 + i
i = 0.0617 * 100%
i= 6.17%

The annual interest rate is 6.17%.