2條precentage問題

1) The interest rate per half a year = 4%/2 = 2%
The total interest earned after 2 years
= 16000 x (1 + 2%)^4 - 16000
= 17318.9 - 16000
= $1318.9
2) The interest rate per quarter = 16%/4 = 4%
Amount that Sunny will owe after 1 year
= (((20000x(1 + 4%) - 4000)x(1+4%)-4000)x(1+4%)-4000)x(1+4%)-4000
= $6411.3

1.) If the principal is $16000 and the interest rate is 4% p.a. compounded half-yearly, find the total interest earned after 2 years.

$16000(1+4%/2)^4-$16000
=1318.91456
Therefore, the total interest earned after 2 years is $1318.9


2.)Sunny borrows $20000. The interest is calculated at the interest rate of 16% p.a. compounded quarter-yearly. If he repays $4000 every 3 months, how much will he owe after 1 year?

1st 3 months: $20000(1+16%/4)-$4000
=$16800
2nd 3 months: $16800(1+16%/4)-$4000
=$13472
3rd 3 months: $13472(1+16%/4)-$4000
=$10010.88
4th 3 months: $10010.88(1+16%/4)-$4000
=$6411.3125

Therefore, he will owe $6411.3 after 1 year.