A savings bank offers long-term savings certificates at 721% per year, compounded continuously. If a 10-year certificate costs $1000, what will be its value at maturity? Compare with the value that would be obtained if the interest were compounded annually rather than continuously.
From (5.2),
F/P=em (5.2)
F = P × [F/P, r%, n] = $1000e(0.075)(10) = 42117.00
This problem can also be solved using Appendix C. Since a table is not available for a nominal interest rate of 721% per year, however, it will be necessary to interpolate between the 7% and 8% values.
[F/P, 7%, 10] = 2.0138 [F/P, 8%, 10] = 2.2255
and [F/P, 721%, 10] = 2.0138 + 8.0 – 7.07.5 – 7.0 (2.2255 – 2.0138) = 2.1197
The future worth of the savings certificate can now be obtained as
F ≈ $1000(2.1197) = $2119.70
If the interest were compounded annually rather than continuously, the future worth would be
F = $1000(1+ 0.075)10 = $2061.00
or $56 less than the amount that is obtained with continuous compounding.