| The Problem |
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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
b). Graph f and the data together.
Solution:
To obtain a scatterplot for
the data, first set the WINDOW to:[1955, 2005, 5] by [10, 25,
5].
Press WINDOW and enter 1955 for Xmin, 2005 for Xmax,
5 for Xscl, 10 for Ymin, 25 for Ymax, and 5 for Yscl.
Next, to graph the scatterplot, Press Y= . Notice if PLOT1 is highlighted. If it is not as in the first image below, press the UP ARROW KEY to highlight PLOT1, and then press ENTER. In either case, next press GRAPH to view the scatterplot.
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To graph function
f on the same screen, the function, 
must be entered on the Y= screen for
.
Since the numbers have many digits, this is difficult. Rounding off causes
error, so let the calculator copy the regression function into .
Press STAT,
the RIGHT ARROW KEY to CALC, and select 6:CubicReg.
Then press VARS, the RIGHT ARROW KEY to Y-VARS,
ENTER to select 1:Function, ENTER to select ,
and then ENTER to calculate the regression. The function formula
has been copied into ,
so now press GRAPH to view the graph.
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