Question

Suppose the line of best fit for some data points has a slope of 1.885. If the mean of the x-coordinates of the data points is 3.448, and the mean of the y-coordinates is 12.318, what is the y-intercept of the line to three decimal places?

Answer 1

Step-by-step Answer:

One of the properties of a least-squares regression line (line of best fit) is that the line always passes through the point (xbar, ybar).

Assuming the given "line of best fit" is a least-squares line, then we are given

a slope m=1.885 passing through (x0,y0)=(3.448,12.318).

Applying the standard point-slope formula:

(y-y0) = m (x-x0)

we get

y-12.318 = 1.885(x-3.448)

Expand and simplify,

y=1.885x -1.885*3.448 + 12.318, or

y=1.885(x) + 5.81852

(numbers to be rounded as precision dictates).