Question 965515
here's an online statistics calculator that will help.
<a href = "http://www.alcula.com/calculators/statistics/" target = "_blank">http://www.alcula.com/calculators/statistics/</a>


you would take your data and enter it into the regression calculator.


it will then generate a scatter plot and a trend line for you.


you enter the x and y values as x,y on each line.


x is the number of people in each household and y is their monthly water bill.


the input will look like this:


<img src = "http://theo.x10hosting.com/2015/042301.jpg" alt="$$$" </>


you enter your x value and y values for each pair of data as x,y.


x is the number of people in the household and y is the monthly water bill for that household.


you can use the scatter plot generator to get a scatter plot of the data.


this plots the x values on the x axis and the y values on the y axis.


the output of that looks like this:


<img src = "http://theo.x10hosting.com/2015/042302.jpg" alt="$$$" </>


you use the regression calculator to generate your trend line.


that output looks like shis:


<img src = "http://theo.x10hosting.com/2015/042303.jpg" alt="$$$" </>


you get the correlation coefficient by running the correlation coefficient calculator.


that output looks like this:


<img src = "http://theo.x10hosting.com/2015/042304.jpg" alt="$$$" </>


the r^2 value tells you how good your fit is.


r^2 is the valuoe or r squared.


with this data, r^2 will be equal to roughly .98515 square = .97052 which is a pretty good fit.


any r^2 greater than .9 is a good fit.


your regression calculator tells you that:


the equation for the line of best fit is y = 0.61 * x - 0.33


the calculator shows you much more accuracy, but for practical purposes, this is good enough to get the general idea of how that equation will look on a graph.


if youo need a tutorial on correlation and regression, then the following links might be helpful.


<a href = "http://www.regentsprep.org/regents/math/algebra/AD4/indexAD4.htm" target = "_blank">http://www.regentsprep.org/regents/math/algebra/AD4/indexAD4.htm</a>