If a certain sum of money invested at a certain rate of compound interest doubles in 6 years. In how many years will it become 8 times?

A sum of money becomes Rs.6690 after three years and Rs.10,035 after 6 years on compound interest. The sum is

Rs.1600 at 10% per annum compound interest compound half-yearly amount to Rs.1944.81 in

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

The difference in C.I and S.I for 2 years on a sum of money is Rs.160. If the S.I for 2 years be Rs.2880, the rate percent is :

The value k of a machine depreciates every year at the rate of 10% on its value at the beginning of that year. If the present value of the machine is Rs.729, its worth 3 years ago was :

The least number of complete years in which a sum of money put out at 20% C.I. will be more than doubled is :

A sum of Rs.550 was taken a loan. This is to be repaid in two equal annual instalments. If the rate of interest be 20% compounded annually, then the value of each instalment is :

A loan was repaid in two annual instalments of Rs.112 each. If the rate of interest be 10% per annum compounded annually, the sum borrowed was :

A sum amounts to Rs.2916 in 2 years and to Rs.3149.28 in 3 years at compound interest. The sum is :