How long will it take for a sum of money to triple at $20\%$ annual compounded quarterly.

Effective and nominal interest rate

The nominal rate of interest is the annual rate of interest quoted by financial institutions. It does not take into consideration that sometimes interest is added to the principal during the course of the year.

The effective rate of interest is the equivalent simple interest rate due to the compounding effect of $$m$$; times per year

EIR$=(1+$ I $/$ M $)$ M $-1$