P=4000
R=10%
Times =2.5 years
First take n=2 years
A=P(1+r100)n=4000(1110)2
4000(121100)
A=4840
Simple interest for last 12 years is PRT100
=4840×10100×12
=242
Amount after 212 year =4840+242
=5082
Compound interest =5082−4000
CI=1082.
Hence, the compound interest, CI=1082