Question

Please, can someone help me!! I need to graph a scatter plot involving the height and arm span of 6 people but I don't have the software to do it and I can't download it either, I don't know why? But anyway, the points are:

66 inches tall arm spam 65,
57 inches tall, arm span 58 inches.
61 inches tall, arm span 61.5,
75 inches tall, arm span 75.
62 inches tall, arm span 61.75,
63 inches tall, arm span 64.

I also have to determine the line of best fit. So if you could tell me which two points you used to draw the line of best fit, you would be a real life saver!!

Answer 1

Can anyone help me??? I really need to get this done but if I can't graph it then I'm kind of screwed!! Unless someone knows a good graphing website that actually works and I don't have to pay for it!!! That would be great to!! Get back to me as soon as possible!!! Please and Thank You!!! :D

Answer 2

Do you have excel?

Answer 3

Excel does a line of best fit. If you do not (or if you want a simpler program), go to http://www.padowan.dk/graph/ and download the program. It is free.

Answer 4

Yeah, I've tried excel, CNET graph, geogebra and MathGV but nothing works!! :'( Every time its almost done downloading it says theres an error and that this program was unable to be installed??? I don't know why, I think my computer is retarded!! Any other suggestions?? I have to find someway to get this done!!

Answer 5

Can anyone help me on this?

Answer 6

I think the computer needs to checked for a virus.

Answer 7

Using the height as x and span as y, the CNET graph gave
f(x)=0.94148936*x+3.9530142

Answer 8

Do you think you could do it again but with these points? I know I'm asking a lot but nothing on my computer works. Im taking it down to my uncle who repairs computers to see what he can do for me? And can you tell me what two points make up the line of best fit??

66,65
57,58
61,61.5
75,75
62,61.75
63,64
55,54
62.5,61.5
68,70.75
61.5,63.25
74,77.75

Answer 9

The program gives f(x)=1.1091566*x-6.3141248

Answer 10

I also have to answer these questions, Idk if you'd be willing to help with these as well? You don't have to though..

Write the equation of the line passing through those two points using the point-slope formula
y - y1 = m(x - x1). Show all of your work. Remember to find the slope of the line first.
What does the slope of the line represent within the context of your graph?
Using the equation that you found in question 2, approximately how tall is a person whose arm span is 66 inches?
According to your line of best fit, what is the arm span of a 74-inch-tall person?

Answer 11

The program does not actually have the line go through two of the specific points in your list.

Answer 12

Btw I really appreciate you doing this for me. I don't know what I would have done, I cant get my computer fixed until maybe next week and I dont have that much time to wait.

Answer 13

What do I do then? How do I answer the question then?

Answer 14

How do I even find the line of best fit? I don't understand when it says its I just have to "eyeball it", what is that suppose to mean?

Answer 15

The line of best fit is a line that comes closest to matching all the points.

Answer 16

so what are the two points? are they the points the line passes through?

Answer 17

could you help me with those other questions to?

Answer 18

is there any way you could send me the graph?

Answer 19

Looking at the graph, I would choose two points on the line- one one each end.

Answer 20

but there is only one point that falls one the line?

Answer 21

They do not have to be points on your list.
Maybe (57, 57) and (76, 78)

Answer 22

ohhh okay

Answer 23

hold on one sec

Answer 24

Using the two points, your equation of best fit will be slightly different from the one given by the graph program.

Answer 25

Do you know how to use the two points to find the slope?

Answer 26

im trying to do the other questions and could you tell me if im right when im done with them.

Answer 27

m = Y2-Y1/X2-X1 right?

Answer 28

Yes.

Answer 29

Is the slope 21/19?

Answer 30

or do I have to simplify it?

Answer 31

21/19 is correct and already simplified.

Answer 32

okay now I plug it into Y-Y1=M(X-X1) right?

Answer 33

Yes

Answer 34

awww man Im stuck at Y-57=21/19(x-57) I know you distribute 21/19 to 57 but it doesn't look right to me?

Answer 35

would you get: Y-57=21/19X-1197/19? I guess im asking a pretty basic question.... when you distribute you multiply??? or divide im drawing a blank.....

Answer 36

do you multiply*

Answer 37

19 goes into 1197 63 times

Answer 38

So what you have is correct.
y - 57 = (21/19)x - 63

Answer 39

and now I subtract 57 from 63and get Y=21/19X-6 right?

Answer 40

Correct.

Answer 41

and thats point slope form!! :D

Answer 42

slope-intercept form

Answer 43

OHHH right!! sorry lol. I have one more, what does this mean? what does the slope of the line represent within the context of your graph?

Answer 44

Y-57=21/19 * (x-57)
This was the point-slope form.

Answer 45

ohhh wow

Answer 46

Remember that the 21 is the change in the y, or the arm span.
19 is the change in the x, or the height.

Answer 47

I cant believe I missed that one....

Answer 48

So the slope means that as the height increases 19 inches the arm span will tend to increase 21 inches.

Answer 49

They are easy to miss until you really learn them well.

Answer 50

yeah plus i'm not very good in math so its even harder... wait, was that the answer to what does the slope of the line represent within the context of the graph?

Answer 51

Yes

Answer 52

21 is the change in the y, or the arm span.
19 is the change in the x, or the height.
So the slope means that as the height increases 19 inches, the arm span will tend to increase 21 inches.

Answer 53

okay thank you so much :D

Answer 54

You're welcome.

Answer 55

Have a good night!

Answer 56

You too.

Answer 57

Ummm maybe im not done.... sorry to keep going on but I have two other questions:

Using the equation that you found in question 2, approximately how tall is a person whose arm span is 66 inches?

Would I solve this like this: Y-57=21/19X-66?

According to your line of best fit, what is the arm span of a 74-inch-tall person?

And for this one would I do: Y-74=21/19X-66?

Answer 58

how would you solve it? im not sure?

Answer 59

wait 2 would be Y-74=21/19X-57?

Answer 60

I would use the equation y=21/19 x - 6,
but the important part to remember is that y is the arm span, so put 66 in for y.

Answer 61

so would I change it to 66=21/19x-6? I really suck at algebra... lol

Answer 62

You're doing alright in my opinion.

Answer 63

haha :)

Answer 64

Now solve for x to get the expected height.

Answer 65

is it 60?

Answer 66

would you replace the x with a 0?