# showing on a scatterplot part of a set of collected data.  An equation for the curve of best fit is y=1/4x^2-2x-3.  How to determind proper data point in the set. (-6,18), (-2.5, 5), (9.0,-2.5),...

showing on a scatterplot part of a set of collected data.  An equation for the curve of best fit is y=1/4x^2-2x-3.  How to determind proper data point in the set.

(-6,18), (-2.5, 5), (9.0,-2.5), (3,-6), (6,-6), (12,9)(15,23)

pramodpandey | Student
fitin curve is y=(1/4)x^2-2x-3. How to determind proper data point in the set ? (-6,18), (-2.5, 5), (9.0,-2.5), (3,-6), (6,-6), (12,9)(15,23) substitute x in fitted curve and calculate y . If calculated y is near to the given y then that is proper data point. let x=6 y= (1/4).(6)^2- 2.6-3 y=9-15 y=-6 It is same as given value. (6,-6) is proper data point.
pramodpandey | Student
Let regression line is y= a +bx (i) sum(y)= n. a+ b sum(x) (ii) sum(xy) =a. sum(x)+ b sum(x^2) (iii) n=7 sum(x)=36.5 sum(y)=40.5 sum(xy)=256 sum(x^2)=537.25 Thus equation reduces to 40.5=7a+36.5b (iv) 256=36.5a+537.25b (v) solving (iv) and (v) for a and b , we have a=5.113 b=.129 Thus best fitted line is Y= 5.113+ .129 X