For the first
year, on interest being compounded at R=12 %, we have
Amount=P(1+R100)N=12,500×(1+12100)1=12,500×1.12=Rs14,000
For the second year, P=Rs14,000 on interest being compounded at R=15 %, we have
Amount=P(1+R100)N=Rs14,000×(1+15100)1=Rs14,000×1.15=Rs16,100
For the third year, P=Rs16,100 on interest being compounded at R=18 %, we have
Amount=P(1+R100)N=Rs16,100×(1+18100)1=Rs16,100×1.18=Rs18,998
Now, C.I. for the first year =A−P=14,000−Rs12,500=Rs1,500
And, C.I. for the third year =A−P=18,998−Rs16,100=Rs2,898
Required difference between the C.I. for the first
year and third year =Rs2,892−Rs1,500=Rs.1,398