To calculate the 3-period moving average for the 4th week, you'll take the average of the time series values from the 3 preceding weeks (Week 1, Week 2, and Week 3).
The values for the relevant weeks are:
- Week 1: 11
- Week 2: 5
- Week 3: 12
Now, calculate the moving average:
\[ \text{Moving Average} = \frac{\text{Week 1} + \text{Week 2} + \text{Week 3}}{3} = \frac{11 + 5 + 12}{3} \]
Calculating that:
\[ = \frac{28}{3} \approx 9.33 \]
Thus, the 3-period moving average forecast for the 4th week is approximately 9.33.