The Problem |
The data in the following table list natural gas consumption ( in quadrillion BTU) in the United States. Estimate the natural gas consumption in 1982. |
Natural Gas Consumption
Year |
1960 |
1970 |
1980 |
1990 |
1997 |
Consumption |
12.4 |
21.8 |
20.4 |
19.3 |
22.6 |
Source: US Department of Energy
a). Find a polynomial function of degree 3 that models the data.
Solution:
A model of degree 3 has been chosen since the data appears to have 2 turning
points.
First clear all lists in the calculator. Press STAT and then 1:Edit. Enter the x-values (the years) in . Now press the RIGHT ARROW KEY so the cursor is in the column and enter the y-values (the consumption).
Press STAT, then the RIGHT ARROW KEY to select CALC , and then select 6:CubicReg for cubic regression. Now press ENTER.
Therefore, the
polynomial function of degree 3 which models the data is:
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