S.O.S. Mathematics CyberBoard

A superannuation fund paid 6% p.a for the first 10 years and then 10% p.a after that. If Bryce puts $5000 into this fund at the end of each year, how much would he have at the end of 25 years?

Future value of periodic deposit D:
F = D[(1+i)^n - 1] / i

With your problem:
F = 1.10^15[5000(1.06^10 - 1) / .06] + 5000(1.10^15 - 1) / .15

Breakdown:
[5000(1.06^10 - 1) / .06] : the 1st 10 deposits plus interest
1.10^15 : interest for 15 years on above
5000(1.10^15 - 1) / .15 : the last 15 deposits plus interest

OK??

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