years $1$ through $11,$ and the instructions are:

a$)$ Plot the data on a graph and look for any trends, cycles, or random variations.

b$)$ Forecast demand from year $4$ to year $12$ using a $3-$year moving average and plot this on the graph.

c$)$ Forecast demand from year $4$ to year $12$ using a $3-$year weighted moving average with weights of $1,3,$ and $6,$ and plot this on the graph.

d$)$ Compare the forecasts with the original data to determine which method provides better results.