Forecasts and actual sales of MP3 players at Just Say Music are as follows:

Month	Forecast	Actual Sales
March	150	170
April	220	229
May	205	192
June	256	241
July	250	238
August	260	210
September	270	225
October	280	179

1. Plot the data and provide insights about the time series.
2. What is the forecast for November, using a three-period moving average?
3. What is the forecast for November, using a two-period moving average?
4. Compute MSE for the two- and three-period moving average models and compare your results.
5. Find the best number of periods for the moving average model based on MSE.