To find a logarithmic model, you first have to enter the values into lists. Push STAT, choose Edit, and then enter the values in the first two columns. Then, press STAT, scroll to right to view the CALC options, and then choose the ninth option in the list, LnReg.
See solution.
Practice makes perfect
We will find a logarithmic model of the form p=a+bln h for the data in Example 6 using a graphing calculator.
Air pressure, p
1
0.55
0.25
0.12
0.06
0.02
Altitude, h
0
5
10
15
20
25
To do so, we first have to enter the values into lists. Push STAT, choose Edit, and then enter the values in the first two columns. Note that the h-values will be written in the first column and the p-values will be written in the second column.
Next, we press STAT, scroll to right to view the CALC options, and then choose the ninth option in the list, LnReg.
As we can see, the result is an error message. To find the reason behind this error, we will examine the scatter plot of the data. Pushing the GRAPH button will tell the calculator to plot the dataset.
Notice that the scatter plot of the data displays as an exponential model. Therefore, we cannot find a logarithmic model and the calculator gives an error.
