Air travel data for Roman Airlines the past 9 (ix, in Romannumerals) weeks are shown below.

Week passengers

1. 459
2. 455
3. 452
4. 446
5. 439
6. 429
7. 432
8. 428
9. 425

1. Calculate the formula for the trend line, using these data. Show your work in obtaining this formula.
2. What is your forecast for week 12 using the trend line equation form part b?
3. What are your forecasts for period 8 and 10 using the five-period moving (unweighted).