Portage Learning Math 110 Module 9 Exam
Exam Page 1
1. Suppose you have 45 data points and you calculate the sample correlation coefficient
and find that r = .32. Can you be 95% confident that a linear relation exists between the
variables? If so, is the relation positive or negative? Justify you answer.
Note that for n=45 and 95% we get a value from the chart of .29396. The
absolute of r is |r|=.32, which is above .29396. So a positive linear relation
exists.
,Exam Page 2
2. Suppose you have 60 data points and you calculate the sample correlation coefficient
and find that r = .20. Can you be 95% confident that a linear relation exists between the
variables? If so, is the relation positive or negative? Justify you answer.
Note that for n=60 and 95% we get a value from the chart of .25420. The
absolute of r is |r|=.20, which is below .25420. So no linear relation exists.
, Exam Page 3
3. Compute the sample correlation coefficient for the following data:
Can you be 95% confident that a linear relation exists between the variables? If so, is
the relation positive or negative? Justify you answer.
n=5 r=-0.966IrI=0.966 c=0.87834 x*=6.4 y*=12 Sx=2.702
Sy=3.54
The absolute value of negative r is greater than the critical value correlation
coefficient. There is a negative linear relation between the variables.
Exam Page 1
1. Suppose you have 45 data points and you calculate the sample correlation coefficient
and find that r = .32. Can you be 95% confident that a linear relation exists between the
variables? If so, is the relation positive or negative? Justify you answer.
Note that for n=45 and 95% we get a value from the chart of .29396. The
absolute of r is |r|=.32, which is above .29396. So a positive linear relation
exists.
,Exam Page 2
2. Suppose you have 60 data points and you calculate the sample correlation coefficient
and find that r = .20. Can you be 95% confident that a linear relation exists between the
variables? If so, is the relation positive or negative? Justify you answer.
Note that for n=60 and 95% we get a value from the chart of .25420. The
absolute of r is |r|=.20, which is below .25420. So no linear relation exists.
, Exam Page 3
3. Compute the sample correlation coefficient for the following data:
Can you be 95% confident that a linear relation exists between the variables? If so, is
the relation positive or negative? Justify you answer.
n=5 r=-0.966IrI=0.966 c=0.87834 x*=6.4 y*=12 Sx=2.702
Sy=3.54
The absolute value of negative r is greater than the critical value correlation
coefficient. There is a negative linear relation between the variables.
