Exponential and logarithmic models

Question

(table)

x) 1 2 3 4 5 6

y) 831 924 1047 1129 1293 1366

use regressions to find an exponential equation that best fits the data above. The equation has form y=ab^x where:

a=______

b=______

Answer 1

Using a TI-84 Plus CE calculator:

Step 1: Hit the "stat" button (4 buttons above the "8"). You will get a screen where "EDIT" is highlighted and "1:Edit. . ." is also highlighted. Press "enter". This will take you to a table where L₁, L₂, L₃, etc are shown. You need to clear the table if there is anything in it. To clear a column of data, use the cursor controls to scroll up and highlight "L1" or any other column that has data. Once the "L1" (or whatever) is highlighted, press "clear" (2 buttons up from the divide symbol) then press enter. Repeat as necessary to clear the entire table. Now, enter the data in your problem. The 1, 2, 3, 4, 5, and 6 go in the L1 column. Scroll to the first space under the L1 column heading and type "1" then enter, etc. Then scroll up to the space under the L2 column heading and type the y-values. It should look like this when done:

Then push the "stat" button, scroll to the right to highlight "CALC" then scroll down and highlight "0:ExpReg" and hit "enter".

You'll get a screen that says:

ExpReg

Xlist: L1

Ylist: L2

FreqList:

Store RegEQ:

Calculate

Make sure that "Xlist" says "L1" (that is where you stored your x-values)

Make sure that "Ylist" says "L2" (that is where you stored your y-values)

If they say something different, you must highlight each one that needs to be corrected and push "list" (2nd stat) and select L1 for Xlist and L2 for Ylist.

Then scroll down to "Calculate" and push "enter".

You will get a screen that says:

ExpReg

y=a*b^x

a=_________

b=_________

These values are the answers to your question. I did not list the answers so you could try it out. After you get your answers, I can let you know if you got them correct.