A sum of Rs. 5120 amounts to Rs. 7290 in 3 years at compound interest. Find the rate of interest per annum.

A sum of Rs 4200 becomes Rs 5082 in 3 years rate simple interest. What is the rate of interest per annum?

A sum of money amounts Rs. 800 in 3 years and Rs. 840 in 4 years at compound interest. What is the rate of compound interest per annum?

A sum of Rs. 16000 earns a simple interest of Rs. 2560 in 2 years. Find the rate of interest per annum.

A sum of Rs. 2400 amount to Rs. 2646 in 2 years. Find the rate of compound interest per annum?

A sum amounts to Rs. 5600 in 4 years and Rs. 6400 in 6 years at a certain rate of simple interest. Find the rate of interest per annum and the sum.