At what simple rate of interest a sum is double in 8 years?

A sum of money was invested at a certain rate of simple interest for 2 years. Had it been invested at 1% higher rate, it would have fetched Rs.192 more interest. The sum of money is-

The simple interest on a certain sum of the money at 4 % per annum for 4 years is Rs.80 more than the interest on the same sum for 3 years at 5 % per annum. Find the sum.

An amount doubles itself in 5 years simple interest. What is the rate of interest per year?

A sum of money becomes 3 times in 12 years. In how many years it will become 5 times at the same rate of simple interest?

Rs. 1,080 invested for 3 months gave an interest of Rs. 27. The simple rate of interest per annum was :

Ms. Deksha borrow Rs. 575 at 5 % per annum simple interest. What amount (in rupees) will she pay to clear her debt after 4 years?

Simple interest on an amount is Rs. 24 and true discount on the same is Rs. 20. The principal amount is