The table named "Sales" to the right, shows the sales of a supermarket (in thousand dollars) in the last 12 months.

Note: to facilitate answering the questions in the next two sheets, use Excel Data Analysis Tool Pack (except for questions 1b and 2d).

Sales
Month	Sales
1	125
2	141
3	125
4	123
5	126
6	145
7	147
8	162
9	155
10	158
11	147
12	159

a) Develop the 2-months and 3-months moving averages for the supermarket sales.

Note: use data analysis tool pack.

b) Which moving average appears to provide more accurate forecasts based on MAD? Explain.

Note: show your MAD calculations.