Question

The enrollment at East Valley High School over a six-year period is displayed in the scatterplot.


Student Enrollment at East Valley High School
On a graph, the x-axis is labeled year and the y-axis is labeled students. Points (2009, 1,330) and (2013, 1,492) are plotted.



Which is the equation of the line of best-fit for this scatterplot?
y = negative StartFraction 81 Over 2 EndFraction x + StartFraction 165,389 Over 2 EndFraction
y = negative StartFraction 2 Over 81 EndFraction x + StartFraction 111,748 Over 81 EndFraction
y = StartFraction 2 Over 81 EndFraction x + StartFraction 103,712 Over 81 EndFraction
y = StartFraction 81 Over 2 EndFraction x minus StartFraction 160,069 Over 2 EndFraction

Answer 1

Slope = (1492 − 1330)/(2013 − 2009) = 162/4 = 81/2.
Use (2009,1330): b = 1330 − (81/2)(2009) = −160,069/2.

So the line is y = (81/2)x − 160,069/2 (the fourth option).