A certain sum becomes $\frac{36}{25}$ of itself after 2 years on compound interest. Find the rate of interest per annum.

A certain amount, when put at a compound rate of interest, becomes double in 5 years. In how many years will the amount become eight times?

In how many years Rs. 100000 will become Rs. 1,33,100 at compound interest rate of 10% per annum?

If the difference between the compound and simple interest on a certain sum of money for 3 years at 5% per annum is ₹15.25, then find the sum.

Simple interest of Rs.10000 for 15 years at 15% PA is equal to simple interest of Rs.15000 at $x$% PA in 10 years. Find the value of $x$.

What will be the simple interest earned on an amount of Rs. 22000 in 8 months at $8\frac{1}{4}\%$ per annum?

Find the compound interest on Rs. 16,000 at 20% per annum for 9 Months, compounded quarterly.