Two mutual fund managers, Martha and David, have been discussing whose fund is the top performer. Martha states that investors bought shares in her mutual fund ten years ago for $21.00 and those shares are now worth $65.00. David states that investors bought shares in his mutual fund for only $3.00 six years ago and they are now worth $7.30. Which mutual fund manager had the higher growth rate for the management period? Should this comparison be made over different management periods? Why or why not?