What is the rate of interest per annum for simple interest at which Rs.880 amounts to Rs.913 in years?

A person invests a certain amount on simple interest. After 8 years he gets 16% interest. If he invests the same sum for 4 years, then he gets Rs. 9600 as interest, then the sum is

Manoj deposited ₹ 29400 for 6 years at a simple interest. He got ₹ 4200 as interest after 6 years. The annual rate of interest was-

In 5 years, the simple interest on an amount of Rs. X is of the principal. The rate of interest per annum is:

What will be the ratio of the interests earned by identical sum of money invested at the same rate of simple interest for 6 years and for 15 years respectively?

At what rate per cent per annum will a sum of money double in 8 years?

There is 80% increase in an amount in 8 years at simple interest. What will be the compound interest on Rs. 15,000 after 3 years at the same rate of interest?

In what time will ₹ 72 become ₹ 81 at % per annum simple interest?