Rs. 'm' is invested in scheme 'A' for 3 years offering 20% simple interest per annum, and Rs. (m - 4000) is invested in scheme 'B' for 2 years offering 25% compound interest compounded annually. If the sum of the interest earned from both schemes is Rs. 9400, find the value of 'm'.

A sum becomes 25 times of itself when invested for 48 years at r% simple interest per annum. Find the compound interest earned if Rs. 51,200 is invested at r% per annum when interest is compounded half-yearly, for 1.5 years.

Simple interest on a certain sum at 4% per annum for 2 years is ₹80. What is the compound interest on the same sum for the same period at the same rate?