Question $1$:

Consider the following demand data

t Sept Oct Nov Dec Jan

xt $109115116109125$

a$)$ Forecast the demand using a Moving Average with N$=6$ after each of the next $5$ months if the actual demand is as follows:

t Feb Mar April May June

xt $130122128117129$

b$)$ Repeat part a$)$ using exponential smoothing with $=0\mathrm{.}3.$

c$)$ Plot the data, along with the forecasts on a graph. Does it look like there has been a change to the underlying model?