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:9. The regression line for a scatter diagram is an
approximation of its graph of averages. For some scatter
diagrams, all of the points of the graph of averages lie on a
straight line. This straight line is then the regression line.
For other scatter diagrams, the points of the graph of averages
do not all lie on a straight line, and so, of course, they do not
all lie on the regression line.
+ Now consider the six scatter +J
diagrams of diagram ? on page ?? of the test. The points of the
graph of averages all lie on the regression line of
a. all

b. one

c. two

d. three

e. four or five

of the six scatter diagrams.