You observe the following sequence of weekly prices and returns for ABC stock:

Week Price Return

$10-$Sep$-2368000$

$17-$Sep$-2362500-8\mathrm{.}09\%$

$24-$Sep$-237000012\mathrm{.}00\%$

$1-$Oct$-23724003\mathrm{.}43\%$

a$)$ What is the arithmetic average weekly return over these three weeks?

b$)$ What is the geometric average weekly return over these three weeks?

c$)$ Explain the usefulness of both the arithmetic and geometric average returns.