SOLUTION: We were given a set of data points today in class. We were told to find an equation for these data points. The equation pertains to graphing so I put the question in this categor

Algebra ->  Graphs -> SOLUTION: We were given a set of data points today in class. We were told to find an equation for these data points. The equation pertains to graphing so I put the question in this categor      Log On


   

Question 152574: We were given a set of data points today in class. We were told to find an equation for these data points. The equation pertains to graphing so I put the question in this category. I'm studying Patters & Relationships in Algebra 2 currently. Data is the X and Y coordinates.
X........Y
610.....915
631.....946
652.....978
673.....1009
Here's what I know from looking at this:
1) The X is independent variable, Y is dependent variable.
2) It is NOT linear because there is not linear progression in the Y
The equation I think might be correct is Y=.0165*X^3
Yet I contractdict it when I plug in the actual X coordinates for example..
Y=.0165*610^3
Y=.0165*226981000
Y=3745186.5 when it should be 915? What is up with that?
Please provide me with the correct equation and tell me how you found it. Thanks!
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
X........Y
610.....915
631.....946
652.....978
673.....1009 

Although it's not perfectly linear, it comes very
close.  To get the best fitting line, called the 
regression line, you have to plug those into a 
god-awful formula, but if you have a TI-83 or 
TI-84 calculator, you can get it easy.

From the cleared main screen,

Press STAT
Press ENTER

Type in the numbers for X in L1
Type in the numbers for Y in L2

Press STAT
Press right arrow
Press 4           ----> You should see LinReg(ax+b)
Press ENTER

Read this

LinReg
 y=ax+b
 a=1.495238095
 b=2.804761905
 
So the equation is Y=aX+b or

Y = 1.495238095X + 2.804761905

If you substitute 

X=610, you get Y=914.9 which rounds to Y=915
X=631, you get Y=946.3 which rounds to Y=946
X=652, you get Y=977.7 which rounds to Y=978
X=673, you get Y=1009.1 which rounds to Y=1009 

Edwin