Final answer:
To forecast for period 6 using a five-period moving average, you would need to calculate the average of the data for the first five periods.
Step-by-step explanation:
To forecast for period 6 using a five-period moving average, you would need the data for the first five periods. Let's say the data for the first five periods is 18000, 17500, 17000, 18000, and 18500. To calculate the forecast for period 6, you would take the average of these five values: (18000 + 17500 + 17000 + 18000 + 18500) / 5 = 17800. Therefore, the closest answer would be 1. 17825.