You have the following rates of return for a risky portfolio for several recent years. Assume that the stock pays $1 dividend at year end. Year 2004 2005 2006 2007 Beginning of year price $50 $55 $51 $54 # shares bought or sold 100 bought 50 bought 75 sold 75 sold a. What is the arithmetic average return over the entire time period? b. What is the geometric average return for the period