The following table shows the monthly sales of refrigerators at a local Home Depot

for

February to August of $2023.$

Month Sales

Foreca

st

$1$ February $19$

$2$ March $18$

$3$ April $15$

$4$ May $20$

$5$ June $18$

$6$ July $22$

$7$ August $20$

$8$

Septemb

er $?$

a$.$ Use Excel to plot the monthly data and comment on sales of refrigerators over this

time period.

b$.$ Forecast September sales volume using a na$$ve approach.

c$.$ Forecast sales for May through September using a three$-$month moving average.

d$.$ Forecast sales volume for May through September using a three$-$month weighted

average with

weights $0\mathrm{.}50,0\mathrm{.}30,$ and $0\mathrm{.}20$

e$.$ Forecast sales volume for February to September using the exponential smoothing

approach

with smoothing coefficient of $\backslash$alpha $=0\mathrm{.}60.$ To start the forecast, use a forecasted value

of $19$ for

February.