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

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?

 If 64 amount to 83.20 in 2 years what will ₹ 86 amount to in 4 years at the same rate percent per annum? 

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

What sum of money must be given as simple interest for six months at 4% per annum in order to earn 150 interest?

A person deposited ₹15,600 in a fixed deposit at 10% per annum simple interest. After every second year he adds his interest earned to the principal. The interest at the end of 4 years is:

Rinky borrowed a certain sum of money from Kajal under the following repayment scheme based on simple interest. 8% p.a. for the initial 2 years, 9.5% p.a. for the next 4 years, 11% p.a. for the next 2 years, 12% p.a. after the first 8 years. Find the amount which a sum of Rs. 9000 taken for 12 years becomes at the end of 12 years?

Alipta got some amount of money from her father. In how many years will the ratio of the money and the interest obtained from it be 10:3 at the rate of 6% simple interest per annum?