QUESTION $2$

$16$ points

Demand for a particular type of battery fluctuates from one week to the next. A study of the last six weeks provides the following demands $($in dozens$)$: $8,9,7,8,10,12($last week$).$

$($a$)$ Forecast demand for the next week using a three$-$week moving average.

$($b$)$ Forecast demand for the next week using a four$-$week moving average.