Suppose Your Capital Today Is $\$ 1000$ , and in Each of the Following Four Years Your

Suppose your capital today is $\$ 1000$ , and in each of the following four years your capital increases to $\$ 1600$ , $\$ 2000, \$ 2400$ , and $\$ 2640$ , respectively. Find the average yearly percentage increase. (Hint: First find the percentage that each succeeding year is based on the value in the preceding year. Then find the geometric mean of the percentages.)