how to plot a scatter diagram and find the best fit quadratic equation?

[fannys4ra]

hello, I need help with this question:

an engineer collects data showing the speed (S) of a given car model and its average miles per gallon (M)
a- use a graphing calculator or appropiate mathematical/computer software (on a pc) to plot the scatter diagram.
b- what is the quadratic function of best fit?

data table
speed, S MPH, M
20 18
30 20
40 23
50 25
60 28
70 24
80 22


i tried to do the graph in excel but i'm not sure that what i'm doing is right.
i need help pleaseeee

thank you so much.

 

[stapel]

an engineer collects data showing the speed (S) of a given car model and its average miles per gallon (M)
a- use a graphing calculator or appropiate mathematical/computer software (on a pc) to plot the scatter diagram.
b- what is the quadratic function of best fit?

data table
speed, S MPH, M
20 18
30 20
40 23
50 25
60 28
70 24
80 22


i tried to do the graph in excel but i'm not sure that what i'm doing is right.

Since we can't see what you've done, we are even less sure about the correctness of your work.

About which part of this exercise are you asking for assistance? Did your class not cover how to use your graphing calculator?

 

[fannys4ra]

no, they didn't cover it because this is an extra credit project.
I figured out how to do the scatter graph. how do i figure which quadratic function best fits now

 

[Deleted member 4993]

no, they didn't cover it because this is an extra credit project.
I figured out how to do the scatter graph. how do i figure which quadratic function best fits now

If you have a PC with MS_EXCEL software - it could be done easily.

 

[Ishuda]

Essentially what you are asking is for a solution to a least squares problem, see
http://www.personal.psu.edu/jhm/f90/lectures/lsq2.html
for example. The final equations can be put in matrix form as given in the link or as three equations in three unknowns which needs to be solved. There are standard solutions and, as Subhotosh Khan poined out, MS_EXCEL has that capability.