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Question
Find the trend of production by the method of a five-yearly period of moving average for the following data:
| Year | Production ('000) |
| 1979 | 126 |
| 1980 | 123 |
| 1981 | 117 |
| 1982 | 128 |
| 1983 | 125 |
| 1984 | 124 |
| 1985 | 130 |
| 1986 | 114 |
| 1987 | 122 |
| 1988 | 129 |
| 1989 | 118 |
| 1990 | 123 |
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Solution
Computation of five-yearly moving averages
| Year | Production ('000) |
5-Yearly centred moving total |
5-Yearly moving averages |
5-Yearly centred moving averages |
| 1979 | 126 | - | - | - |
| 1980 | 123 | - | - | - |
| 1981 | 117 | 619 | 123.8 | |
| 123.6 | ||||
| 1982 | 128 | 617 | 123.4 | |
| 124.1 | ||||
| 1983 | 125 | 624 | 124.8 | |
| 124.5 | ||||
| 1984 | 124 | 621 | 124.2 | |
| 123.6 | ||||
| 1985 | 130 | 615 | 123 | |
| 123.4 | ||||
| 1986 | 114 | 619 | 123.8 | |
| 123.2 | ||||
| 1987 | 122 | 613 | 122.6 | |
| 121.9 | ||||
| 1988 | 129 | 606 | 121.2 | |
| 1989 | 118 | - | - | - |
| 1990 | 123 | - | - | - |
The last column gives the trend in the production by the method of the five-yearly period of moving average.
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