Payments of $1800 and $2400 were made on a $10 000 variable-rate loan 18 and 30 months after the date of the loan. The interest rate was 11.5% compounded semiannually for the first two years and 10.74% compounded monthly thereafter. What amount was owed on the loan after three years?

10 000 1800 2400 ?

{________________________|_________________|______ |___|______________________|

18 months 24months 30months 36months

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11.5% / 2 10.74/12

( for the first 18 months the interest rate is 11.5% compounded semi annually after 6 months which is month number 24 the interest rate is 10.74% compounded annually )

FV = PV ( 1 + i ) ^ n

10 000 ( 1 + 11.5/2 ) ^ 2 * ( 1.5 )

16 774.59

16 774.59 - 1800 = 14 974.59

14 974.59 ( 1 + 0.115/2 ) ^ 2 ( 0.5 )

8 373.09

8 373.09 ( 1 + 0.4074/12 ) ^ 0.5 * 12

100 925.71

100 925.71 - 2400 = 98 525.71

98 525.71 ( 1 + 0.1074 / 12 ) ^ 0.5 * 12

1 187 587.57

I don't know if i did this correctly if not then where did i go wrong?