Eight students, randomly selected from a large class, were asked to keep a record
of the hours they spent studying before the midterm examination. The following
table gives the number of hours these eight students studied before the midterm
and their scores on the midterm.
Hours studied 15 7 12 8 18 6 9 11
Midterm score 97 78 87 92 89 57 74 69
a)

Do the midterms scores depend on hours studied or do hours studied depend
on the midterm scores? Do you expect a positive or a negative relationship
between these two variables?
b)

Taking hours studied as an independent variable and midterm scores as a
dependent variable compute
S
XX
,
S
YY
and
S
XY
.
c)

Find the least squares regression line.
d)

Interpret the meaning of the values of
a
and
b
calculated in part (c).
e)

Plot the scatter diagram and the regression line.
f)

Calculate
r

.

g)

Calculate also the coefficient of determination.