$(3)$ Exponential smoothing with a smoothing constant equal to $\mathrm{.}20,$ assuming a March forecast of $19(000).$

$(4)$ The naive approach.

$(5)$ A weighted average using $\mathrm{.}60$ for August, $\mathrm{.}30$ for July, and $\mathrm{.}10$ for June.

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