28. The difference between simple interest and compound interest on a sum for 2 years at 8% when the interest is compounded annually is Rs.16. If the interest were compounded half yearly, the difference in two interests would be nearly:

29. A sum of Rs. 12000 deposited at compound interest becomes double after 5 years. After 20 years it will become

30. If Rs. 7500 are borrowed at C.I. at the rat of 4% per annum, then after 2 years the amount to be paid is: