Using high school math to work out the annual interest rate of Kobe Bryant’s brilliant investment

Kobe Bryant became a NBA legend with his smooth moves on the basketball court, it appears that he has some smooth moves off the court as well.  According to espn Kobe Bryant’s 6 million investment grew to become 2oo million in about four and a half years. http://www.espn.com/nba/story/_/id/24384862/kobe-bryant-6m-investment-sports-drink-now-worth-200m   An application of the mathematics taught in the 11th grade is to work out the annual interest rate of Bryant’s investment using the compound interest formula. The following article discusses what investors should consider a “good rate of return”, and suggests that 15% to 20% is high and too much to…