Homework SourseThe following trend line and seasonal indexes were computed
The following trend line and seasonal indexes were computed from 4 weeks of daily observations. Forecast the 7 values for next week. y = 120 + 2.3t t = 1, 2, … , 28
Day
Seasonal Index
Sunday
1.5
Monday
.4
Tuesday
.5
Wednesday
.6
Thursday
.7
Friday
1.4
Saturday
1.9
| Day | Seasonal Index |
| Sunday | 1.5 |
| Monday | .4 |
| Tuesday | .5 |
| Wednesday | .6 |
| Thursday | .7 |
| Friday | 1.4 |
| Saturday | 1.9 |
Solution
The equation giving the relation between x and y is given as
y =120+2.3t
Using this for various values of t y is predicted as follows:
| t | 2.3t | 2.3t+120=y |
| 1 | 2.3 | 122.3 |
| 2 | 4.6 | 124.6 |
| 3 | 6.9 | 126.9 |
| 4 | 9.2 | 129.2 |
| 5 | 11.5 | 131.5 |
| 6 | 13.8 | 133.8 |
| 7 | 16.1 | 136.1 |
| 8 | 18.4 | 138.4 |
| 9 | 20.7 | 140.7 |
| 10 | 23 | 143 |
| 11 | 25.3 | 145.3 |
| 12 | 27.6 | 147.6 |
| 13 | 29.9 | 149.9 |
| 14 | 32.2 | 152.2 |
| 15 | 34.5 | 154.5 |
| 16 | 36.8 | 156.8 |
| 17 | 39.1 | 159.1 |
| 18 | 41.4 | 161.4 |
| 19 | 43.7 | 163.7 |
| 20 | 46 | 166 |
| 21 | 48.3 | 168.3 |
| 22 | 50.6 | 170.6 |
| 23 | 52.9 | 172.9 |
| 24 | 55.2 | 175.2 |
| 25 | 57.5 | 177.5 |
| 26 | 59.8 | 179.8 |
| 27 | 62.1 | 182.1 |
| 28 | 64.4 | 184.4 |
