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 $x$.

Ravi invested at compound interest amounts to Rs 600 in 2nd year and 642 in 3 years. what rate of interest per annum he recevied ?

A certain sum on $13\frac{1}{2}\%$ per annum simple interest amounts to Rs. 2502.50 in 4 years. Find the sum.

What is the rate of simple interest for the last 5 years if the sum of ₹ 480 becomes ₹ 792 in 11 years and the rate of interest for the first 6 years is 5%?

A sum of Rs. 1500 is invested at 5% p.a. simple interest. If the interest is added to the principal after every 10 years, the amount will become Rs. 3000 after :

What is the compound interest earned on Rs. 80,000 at 40% per annum in one year, compounded quarterly?

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