Question

Of the following data there is the following two questions.

7. Using the line of best fit that you found in Part 3, Question 3, approximate how tall is a person whose arm span is 66 inches?
8. According to your line of best fit, what is the arm span of a 74-inch-tall person?


I will attach the line of best fit that I found in comments.

@Will.H

Answer 1

could you zoom out the graph i can't see the x- axis nor the y - axis

Answer 2

Is this okay?

Answer 3

looks fine. But according to the data you have suppose that x = the people's height and y = the arm span you can create a linear function there and then be able to determine the height of a person with an arm span of 66 inches. So the 1st step to do is to get 2 coordinates you made and find the slope. Can you do that?

Answer 4

My coordinates is 66.1 and 64.1 How should I find the slope?

Answer 5

Those aren't coordinates. Coordinates are like this (x,y) in our case it is
(height of a person, Arm span)
And slope formula is
\[\frac{ y2 - y1 }{ x2 - x1 }\]

Answer 6

The arm span is 66.1 and the height is 64.1. Should I only say x and y?

Answer 7

I am sorry. I'm just a tad bit confused.

Answer 8

So this is one coordinate well done we have (66.1 , 64.1) We need another coordinate

Answer 9

i've been through this Assignment you should be having a list of coordinates

Answer 10

Yes, yes. It can be 68.1 and 65.2

Answer 11

So, then 64.1 should be y1 right?

Answer 12

very well. So we have (66.1 , 64.1) and (68.1 , 65.2)
x1 = 66.1
y1 = 64.1
x2 = 68.1
y2 = 65.2

Find the slope

Answer 13

I get 0.55. Is that right?

Answer 14

Good job it is
Now i wonder do you know about the slope intercept formula that allows you to create the linear function?
it is like this
\[y - y1 = m(x - x1)\]
Where m is the slope and y1 is the y value in the 1st coordinate which is 64.1
And x1 is the x value of the 1st coordinate which we have it as 66.1

So you just plug in those data and you'll get you function. i will walk you through it start by plugging in the data we have

Answer 15

y- 64.1= 0.55(x-66.1)?

Answer 16

great. Now can you simplify the expression on the right side? you will have to multiply 0.55 * x
and
0.55 * - 66.1

Answer 17

y-64.1= 0.55x- 36.4

Answer 18

Great. Now the shape of a linear function is
y = mx + b
So you will have to get rid of all terms next to y
Can you do that?

Answer 19

Does that mean I have to work out 0.55x- 36.4?

Answer 20

no. We have
y - 64.1 = 0.55x -36.4
So we want y to be alone in the left side solve that a an equation! we just add 64.1 to both sides.

Answer 21

y= 0.55x-36.4 (+ 64.1)?

Answer 22

good. Simplify...

Answer 23

y= 0.55x+27.7?

Answer 24

yes! That's you linear function and we said that x = the height of a person and y = the arm span
So if we want to know how tall someone is when Arm span is 66 inches means that y = 66in so instead of y add 66 inches and solve for x. can you do that?

Answer 25

So the equation would be 66= 0.55x+ 27.7

Answer 26

What would we do with the x

Answer 27

solve for x.. to do that subtract both sides from 27.7 and then divide both sides of 0.55

Answer 28

we need x to be alone in one side. which is the right side. so you'll have to get rid of all the terms next to x

Answer 29

38.3=0.55

Answer 30

66- 27.7= 38.3 and then I should divide it by 0.55 isn't it?

Answer 31

sorry you right

Answer 32

continue we have
38. 3 = 0.55x
Divide both sides on 0.55

Answer 33

So it will be x= 69.6?

Answer 34

Great! so when a person have an arm span of 66 inches his height will be 69.6 inches. And if you want to confirm that see that the coordinates in your graph (69.6 , 66) exist!
So that's the answer for the 7 question.

Answer 35

Okay thank you very much! Will you please help me with the next one as well?

Answer 36

According to your line of best fit, what is the arm span of a 74-inch-tall person?
Here they want to find y and they gave you x = 74 so plug in those data in the equation we made
y= 0.55x+27.7

Answer 37

I am not sure where to plug in the x=74?

Answer 38

we said x = 74 so what does would equal in the equation?

y = 0.55(74) + 27.7

Answer 39

so what does x *

Answer 40

y= 40.7+ 27.7
y= 68.4
x= 68.4?

Answer 41

Correct! For a person with a 74 inches tall (which is the value of x ) has an arm span of 68.4 (which is y) last step you said x = 68.4 that's wrong it is y = 68.4 because we were solving for y (the arm span)

Answer 42

you can find any Arm span or how tall a person is just remember in the function
y= 0.55x+27.7
The x is the tall of a person in inches
The y is the arm span of a person in inches.

Answer 43

do you get it?

Answer 44

Yes, I do. Thank you. There is only one more question I need help on.

Here it is:
Explain why the equation you wrote to represent a human's arm span is a correlation and not causation.

Can you maybe explain?

Answer 45

@Will.H ?

Answer 46

@ShadowLegendX

Answer 47

Please help me...

Answer 48

Nevermind.

Answer 49

@Will.H
Thank you very much for your help over the past two days. I really appreciate it.

Answer 50

sorry i was away

Answer 51

You welcome. let me know if you have additional questions