Question

purohit borrowed 12000 for 10 years at compound interest and the rate of interest was 5% for the first 3 years, 6% for the nest 4 years 7% for rest 3 years. calculate the compound interest.

Answer 1

Prinicipal=Rs.12000
Time-10years
 5% for the first 3 years
6% for the next 4 years
 7% for rest 3 years. 
Amount for these 10 years is=12000(1+5/100)^3 (1+6/100)^4 (1+7/100)^3
                                              =12000(105/100)^3 (106/100)^4 (107/100)^3 
                                              =12000(1.05)^3 (1.06)^4 (1.07)^3
                                               =21,484(approx)

Compound Interest=Amount-Principal=Rs.9484 Ans.