Find the compound interest if `4000` are invested for `3` years at the rate of `12 1/2 %.p.a`.

Find the compound interest on Rs. 6400 at 25% p.a for 3 years .

The compound interest on Rs. 4000 at 25% p.a. in 3 years :

Find the compound interest on Rs.12000 for 10 years at the rate of 12% per annum compounded annually.

Find the compound interest on Rs. 6,500 for 4 years if the rate of interest is 10% p.a. for the first 2 years and 20% per annum for the next 2 years?