4. A man borrows Rs.4000 from a beak at 71/2 compound interest. At the end of every year he pays Rs. 1500 as part repayment of loan and interest. How much does he still how to the bank after three such instalments:

5. The difference of compound interests on Rs. 800 for 1 year at 20% per annum when compounded half yearly and quarterly is:

6. The compound interest on Rs. 2800 for 1 � years at 10% per annum, is: