:1. Imagine a scatter diagram, with its regression line
passing through it. Now add another point to the scatter
diagram. Suppose this new point lies on the regression line.
Then
a. The regression line of the new scatter diagram is the
same as the one for the original scatter diagram.
b. The regression line of the new scatter diagram cannot
possibly be the same as the one for the original
scatter diagram.
c. In order to tell whether or not the regression line for
the new scatter diagram is the same as the one for the
original scatter diagram, you need more information about
the original scatter diagram and the point which is added
to it.