National Scan, Inc., sells radio frequency inventory tags. Monthly sales for a seven$-$month period were as follows: $($Month$,$ Sales$)($Feb$,19)($Mar$,18)($Apr$,15)($May$,20)($Jun$,18),($Jul$,22)($Aug$,20)$

a$)$ Plot the monthly data.

b$)$ Forecast September sales volume using

$$ The na$$ve approach

$$ Five$-$month moving average

$$ A weighted average using $\mathrm{.}60$ for August, $\mathrm{.}30$ for July, and $\mathrm{.}10$ for June.

$$ Exponential smoothing with a smoothing constant equal to $\mathrm{.}20,$ assuming a March forecast of $19(000).$

$$ A linear trend equation.

c$)$ Which method seems least appropriate? Why? $($Hint: Refer to your plot from part d$)$What does use of the term sales rather than demand presume?