Answer:
Answer: Choice A
y = (-2/3)x + 12
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Work Shown:
We will only focus on the two points that are on the regression line.
Those two points are (3,10) and (12,4)
Let (x1,y1) = (3,10) and (x2,y2) = (12,4)
Find the slope of the line through (x1,y1) = (3,10) and (x2,y2) = (12,4)
m = (y2 - y1)/(x2 - x1)
m = (4 - 10)/(12 - 3)
m = -6/9
m = -2/3
Plug m = -2/3 and (x1,y1) = (3,10) into the point slope formula
Solve for y.
y - y1 = m(x - x1)
y - 10 = (-2/3)(x - 3)
y - 10 = (-2/3)x + (-2/3)(-3) ... distribute
y - 10 = (-2/3)x + 2
y - 10 + 10 = (-2/3)x + 2 + 10 .... add 10 to both sides
y = (-2/3)x + 12
This matches up with what the graph shows because the regression line intersects 12 on the y axis, so the y intercept is 12.
y = (-2/3)x + 12 is in the form y = mx+b with m = -2/3 as the slope and b = 12 as the y intercept.