A sum triple itself in 9 years at simple interest. Find the rate of interest per annum is.

What sum will amount to ₹ 7000 in 5 years at $$3{1\over3}\%$$ simple interest ? 

The simple interest on an amount at the rate of 7 percent for five years is Rs 700. So how much is the principal?

The difference between the simple interest and the compound interest on a certain amount at 5% for two years is 25, what is the amount?

A sum of money becomes Rs 16000 in 6 years at the rate of 25% per annum simple interest. What is the total interest for 6 years?

The simple interest on a certain sum at 15% per annum for 5 year is Rs1500 more to the simple interest on the same at 12% per annum for the same period. Find the sum-

The simple interest on a sum for 5 years is one fourth of the sum. The rate of interest per annum is

A sum of money at simple interest amounts to ₹ 1,012 in $$2{1\over2}\%$$ years and to ₹ 1,067.20 in 4 years. The rate of interest per annum is: