The simple interest on a certain principal sum at 4.5% per annum simple interest for 49 years is ₹8,778. Find the amount payable on the same principal sum in 197 years at 5.5% per annum simple interest.

A sum becomes 2215 of itself in 6 years at simple interest. Find the rate of interest per annum.

In how many years will a sum of ₹5,500 amount to ₹6,600 at a simple interest rate of 5% per annum?

A sum of money amounts to ₹16000 in 6 years at simple interest of 25 percent per annum. What will be the total interest for 6 years?