Question

linear regression on TI-84?

Answer 1

I have to use the chart below to answer multiple questions regarding linear regression, the slope of the line, the x and y intercepts, etc.

x -3, -1, 4, 6, 9, 0
y 22, 11, -28, -46, -72, -1

the first question is to find the equation of the regression line of g(x) as a function of x. My question was does anyone know the steps to do this on the TI-84? TIA

Answer 2

I looked up the steps online and got a as -7.85 and b as 0.62. would my answer for this one be g(x)=-7.85+0.62 or is this wrong?

Answer 3

TI-84 or TI-84 Plus? I have the TI-84 PLus and I can help you if so

Answer 4

mine is the plus as well!

Answer 5

Alright, so get your calculator out and let's get started!

Answer 6

I have it (:

Answer 7

Alright, so there will be a STAT button. Find and hit it. Then tell me when you are done.

Answer 8

got it

Answer 9

Now you can see that 1: Edit... is highlighted. Press enter and then there will be a table. Tell me when you see that. =)

Answer 10

okay I'm on the table

Answer 11

Now you should see L1, L2, and L3. Go into L1 and start putting in the numbers you are given for the x's. For the first one put into your calc 0-3 and then hit enter. Now do the same thing for all of your x's. And remember to put a 0- then the number if it is a negative.

Answer 12

Then do the same thing for your y's. Put them in L2. Tell me when you are done. =)

Answer 13

okay i got my x's and y's done (:

Answer 14

No hit the 2nd button and then the Mode button to get rid of the table. After that you need to hit STAT again and press the right button once. Then you should see a list of saying like; 1:1-Var Stats 2: 2-Var-stats, etcetera. Now go down to the number 4, where it says LinReg(ax+b). Hit enter and tell me when you are done.

Answer 15

opps, Now hit the second button.....sorry

Answer 16

okay i got that part done

Answer 17

Now you will see it says XList: L1, Ylist:L2 and so on and so forth. Now I want you to go down to where it says Store RegEQ: . When Store RegEQ is highlighted, hit the VARS button. Then hit the right button. You will then see 1:Function. Hit that. Then Y1 will he highlighted. Hit enter again. Now you will go back to the Screen where it says XList: L1, Ylist:L2, but now Store REgEQ: will say Y1. Go down and highlight calculate and hit enter. then it will gives you the value of A and B. After you have done this, tell me so I can show you why we set Store RegEQ to Y1.

Answer 18

okay i did that (:

Answer 19

Now you can see it solved for A and B! Now to see why I told you to set Store RegEQ. Go and hit the Y= button at the very top of the calc. You will see that the calc put the information into y1. Hit enter and then hit the GRAPH button. Then it will Graph it.

Answer 20

ohh okay, I didn't know that

Answer 21

I learned this last week. So when I saw the question I thought I would help you out. =) This makes it much easier than working out the problem.

Answer 22

Okay thank you! So would the answer still be y=-7.85+0.62 or no? Still kind of confused about what the equation of g(x) would be

Answer 23

Nope, that would be right: \[g(x)=-7.85x+0.62\]

Answer 24

And no problem! Glad I could help =)

Answer 25

Thank you so much! Do I find the slope of the line on the calculator too?

Answer 26

From my understanding: \[y=ax+b\] A = the slope
B = Where the y-intercept is.
So the slope would be -7.85

Answer 27

ohhh I feel dumb now lol. Thanks (:

Answer 28

No problem =)

Answer 29

it's also asking for the x-intercept. somehow I ended up getting 0.08 but I don't think that sounds right.

Answer 30

Alright, so I am going to walk you though on how to find how out what X equals. So in order to find that out you need to make sure that the y=-7.85x+0.62 is still in the Y1 when you hit the graph. Although there should be a lot of number after the decimal. Hit enter and go the the GRAPH. Once you see the graph I want you to hit 2ND and then TRACE(The second button from the right at the top row). After that a list of options will pop up. Go down to where it says 2: zero and hit enter. On the bottom of the calc's screen it will say Left Bound. You need to put that on the left side of the graph and make sure it is in quadrant 2. Then hit enter. After that it will say Right Bound? So move you curser over to the ling on the right below the x-axis. For this equation it should be in quadrant 4. Then hit enter. After that it will say Guess? Again, hit enter. Then a number will pop up and that will be the exact value of x. And my calc says : X=0.07910628 when Y=0. So yes, you are correct! I know you are offline, so when you look at this just tell me if you need any more help with this. Again, I am glad that I could help you! Have a nice day!

Answer 31

@thatgirl21