Ahmad is looking for an investment tool that will double his money in five years.

a) What interest rate (compounded annually), to the nearest whole percentage, does he have to receive?

b) At that rate, how long will it take the money to triple?

ANS a) 15% b) 7.86 years OR 7 years 10 months

Pls attach the formula used, and explain in detail. Pls do not answer in excel format. Thank you in advance.