有關複利息計法

400000(1+5%)^2
=44100


因為條問題係compounded yearly 即係每年compounded 一次
如果條問題係話compounded monthly 即係每月一次
咁個interest rate 就要除12
個ANS 應該係:

40000(1+5%/12)^24
=44197.65343.....

If interest is compounded yearly
Principal and Interest after 2 years
= $400000 x (1+5%)^2
= $400000 x (1.05)^2
=$441000

If interest is compounded monthly
Principal and Interest after 2 years (= 24 months)
= $400000 x (1+5%/12)^(2x12)
= $400000 x (1.004166667)^24
=$441976.53

2012-07-22 09:10:05 補充：
No offence to anyone:
(1) amount of what?
You have to specify the amount of principal and interest
(2) You also specify the unit. ($). The answer should be in 2 decimal.
(3) Comon sense tells you that the amount of principal and interest together should not be less than principal alone.

amount
=400000(1+5%)^2
=$441000