Question

A line of best fit was drawn for 10 data points. What is the maximum number of these data points that may not actually be on the line

Answer 1

Answer: 10

If the line is a perfect fit, then all 10 points are on the same straight line. On the other side of the spectrum, we could have all 10 points not on the line but close enough to it. If the points are too scattered randomly, or they fit a non-linear curve better, then a linear regression line is a bad idea. You can use a correlation coefficient to determine how best the linear fit is.