4-13Students in a management science class have just received
their grades on the first test. The instructor
has provided information about the first test grades
in some previous classes as well as the final average
for the same students. Some of these grades have
been sampled and are as follows:
STUDENT 1 2 3 4 5 6 7 8 9
1st test grade 98 77 88 80 96 61 66 95 69
Final average 93 78 84 73 84 64 64 95 76
(a) Develop a regression model that could be used to
predict the final average in the course based on
the first test grade.
(b) Predict the final average of a student who made
an 83 on the first test.
(c) Give the values of r andr2 for this model. Interpret
the value ofr 2 in the context of this problem.
4-14Using the data in Problem 4-13, test to see if there is
a statistically significant relationship between the
grade on the first test and the final average at the
0.05 level of significance. Use the formulas in this
chapter and Appendix D.
4-15Using computer software, find the least squares regression
line for the data in Problem 4-13. Based on
theF test, is there a statistically significant relationship
between the first test grade and the final average
in the course?
4-19Bus and subway ridership in Washington, D.C., during
the summer months is believed to be heavily tied
to the number of tourists visiting the city. During the
past 12 years, the following data have been obtained:
past 12 years, the following data have been obtained:
NUMBER
OF TOURISTS RIDERSHIP
YEAR (1,000,000s) (100,000s)
1 7 15
2 2 10
3 6 13
4 4 15
5 14 25
6 15 27
7 16 24
8 12 20
9 14 27
10 20 44
11 15 34
12 7 17
(a) Plot these data and determine whether a linear
model is reasonable.
(b) Develop a regression model.
(c) What is expected ridership if 10 million tourists
visit the city?
(d) If there are no tourists at all, explain the predicted
ridership.
USA 
India