Mr. Yonus had a sum of money and he wants to double them in a period of 5 ½ years. He approached many banks and each bank is offering different interest rates to make that sum double. The interest...

Mr. Yonus had a sum of money and he wants to double them in a period of 5 ½ years. He approached many banks and each bank is offering different interest rates to make that sum double. The interest rates offered by various banks are Bank Muscat 25%, National Bank of Oman 10%, Oman Arab Bank 15% and HSBC 20%.

a) At what rate of simple interest the sum will be doubled as per your calculation?
b) Which bank interest rate is matching with your calculation?

c) Considering the present bank interest rate, how many years it will take to double your amount? Discuss with reason