Question : If INR 2,000 is invested at a simple interest rate of 5% per annum and the interest is added to the principal after 10 years, then in how many years will it amount to INR 4,000 at the same rate of interest?

Question : The simple interest on a sum of money is $\frac {1}{16}$th of the principal and the number of years is equal to the rate per cent per annum. The rate per annum is:

Question : The simple interest on a certain sum for 3 years at 8% per annum is INR 9120 less than the simple interest on the same sum for 7 years at 8% per annum. Find the sum.

Question : If a sum of money becomes INR 6,000 in 3 years and INR 10,500 in 7 years and 6 months at the same rate of simple interest, then what is the rate of interest?

Question : What sum will become INR 9,826 in 18 months if the rate of interest is $2 \frac{1}{2} \%$ per annum and the interest is compounded half-yearly?