Question

Help with regression lines

Answer 1

I can't figure out how to get the Predicted cost part

Answer 2

how did you find 0.08 in that last box?

Answer 3

I have done the question like 6 times and it's always 0.08

Answer 4

what kind of calculator do you have?

Answer 5

TI-84 Plus CE

Answer 6

I enter in the data in L1 and L2 but can never get the answer they get

Answer 7

idk what the CE means, but I have a TI84 plus, so I guess that works

Answer 8

so you have your data into L1 and L2

did you do a LinReg ?

Answer 9

Yes

Answer 10

ok it should say something like ax+b or a+bx

and then spit out what a and b are

Answer 11

b=-467.213 but the answer is always between like 164 to 166

Answer 12

hmm let me try, one sec

Answer 13

I guess what's the predicted cost when the miles is at 0.08?

Answer 14

ok I'm getting 0.08 now

Answer 15

and I'm not getting a number between 164 and 167

but I'm getting pretty close to it

Answer 16

How did you get 0.08?

Answer 17

well I got 0.07877 approx which rounds to 0.08

Answer 18

How?

Answer 19

In LinReg?

Answer 20

yeah using that function

Answer 21

I don't see it in mine :(

Answer 22

it's in the calc menu after you hit the stat key

Answer 23

Calc 4?

Answer 24

yeah

Answer 25

btw make sure your "miles" is in the L1 column

Answer 26

if you put "miles" in the L2 column, you'll have to type in `LinReg(ax+b) L2,L1`

Answer 27

Ohh really? I've been putting it in L2 that must be the problem

Answer 28

Why must the miles go first?

Answer 29

Now I got it a=0.07877

Answer 30

and b is 162.95

Answer 31

because the equation is

cost = ____ + ____ * (miles)

miles is the input

Answer 32

Oh I see so I was doing it backwards

Answer 33

well they put the columns in the wrong order (probably to throw you off)

Answer 34

So Predicted cost should be 162.96?

Answer 35

162.95

Answer 36

I actually have to do this problem again since I already restarted it

Answer 37

no that value goes in the missing box

Answer 38

Oh right

Answer 39

Thanks man! I guess I was getting it wrong because I was entering in L1 and L2 backwards. I have been so confused for over an hour. Thank you!

Answer 40

yeah I made the same mistake but swapping the columns or entering `LinReg(ax+b) L2,L1` addresses the issue

Answer 41

Oh okay

Answer 42

Thank you :D