[mizzdiamonds987]

This table shows the population of a given bacteria colony.

Time(days): 0,3,6,9,12
Population(thousands):95,
120,155,190,250

Let x be the number of days and let y be the population in thousands. Linearize the data and find a regression equation for the linearized data.

a. Ln y=0.0948x+4.3321
b. Ln y=0.0798x+4.5517
c. Ln y=0.0722x+4.7735
d. Ln y=0.0785x+4.8203

I plugged the days and population in the list columns of my TI-83 calculator, but I didn't get any of these results when I pressed LinReg(ax+b) on the STAT CALC screen. Does any one know how to calculate the days and the population in order to get one of these results? Any helpful advice pertaining to solving this problem will be greatly appreciated. Thanks in advance.

[z-man2k7]

O wow

[mizzdiamonds987]

XD

[sweetiepie_165]

Wwwwwwwwwwwwwwwhhhhhhhhhhhhhhhhhhhhhhhhhhaaaaaaaaa aaaaaaaaaaaaaaaaaaattttttttttttttttttttttttttttttt tt

[mizzdiamonds987]

Can anyone answer this?

[sailormars84]

Omg! I might be able to help you. it's been AGES since I did this, but give me a bit & I'll try to help you out.

[raye555]

Sorry, I'm not a math geek. More of a music, language, science geek.

[sailormars84]

Ok, I see what's wrong.

Did you put the data in as:
L1: 0,3,6,9,12
and L2: 95, 120,155,190,250? <-- there's the problem.

The linear regression formula should be in the form: y = ax + b, right?
But all of these answers take the natural log of y (they all say ln y = ...)

And remember, the data in L1 runs on the x-axis, right? And the data in L2 runs along the y-axis.
Well, if the answer is asking you to take the natural log of Y (ln y =), then you have to put the data into L2 as the natural log.

So, when you put the data in during the 1st step, it should look like:
L1: 0,3,6,9,12
and L2: ln 95, ln 120,ln 155, ln 190, ln 250

Then, do the same procedure - go to STAT, CALC, LinReg (ax + b), Enter
You should get the right answer. ^_^

There may be another way to do this, but that's the only way I know to do it.
Good luck!

[mizzdiamonds987]

sailormars84 wrote: Ok, I see what's wrong. Did you put the data in as: L1: 0,3,6,9,12 and L2: 95, 120,155,190,250? <-- there's the problem. The linear regression formula should be in the form: y = ax + b, right? But all of these answers take the natural log of y (they all say ln y = ...) And remember, the data in L1 runs on the x-axis, right? And the data in L2 runs along the y-axis. Well, if the answer is asking you to take the natural log of Y (ln y =), then you have to put the data into L2 as the natural log. So, when you put the data in during the 1st step, it should look like: L1: 0,3,6,9,12 and L2: ln 95, ln 120,ln 155, ln 190, ln 250 Then, do the same procedure - go to STAT, CALC, LinReg (ax + b), Enter You should get the right answer. ^_^ There may be another way to do this, but that's the only way I know to do it. Good luck!

Thanks. Now I know what I did wrong. Your a genius

[skaar]

Yes, not a math problem, a calculator use problem. i have a calculus book, i haven't been able to get past the first two chapters without grinding to a good firm halt, i halfarse my way through trig and algebra, i had an idea what you were asking for, but was far from sure.