A manager has been using a certain technique to forecast demand for gallons of ice cream for the past six periods. Actual and forecasted amounts are shown below.

Period	Demand	Forecast
1	85	75
2	96	100
3	102	105
4	85	87
5	74	68
6	69	65

1. What is the MAD for this forecasting technique?

		4.83
		4.95
		4.85
		5.05
		None of the other options are correct

2. What is the MSE for this forecasting technique?

		36.20
		29.50
		None of the other options are correct
		35.55
		40.75

3. What is the sigma (or standard deviation) for this forecasting technique?

		6.017
		3.087
		None of the other options are correct
		4.025
		5.025

4. If the errors are assumed to be normally distributed with CL=0, LCL= -4.5 and UCL= +4.5, the errors

		None of the other options are correct
		Period 1 and 5
		All periods are out of control
		Period 2 and 3
		Period 1 and 4