A store wishes to predict net profit as a function of sales for the next year. The following table gives the years 1998 to 2005.
|
Year
|
Sales
(thousands of dollars)
|
Net Profit
|
|
1998
|
48
|
8.0
|
|
1999
|
52
|
9.4
|
|
2000
|
53
|
11.3
|
|
2001
|
78
|
8.6
|
|
2002
|
80
|
6.6
|
|
2003
|
70
|
4.1
|
|
2004
|
62
|
?1.0
|
|
2005
|
55
|
?2.0
|
(a) Graph the points from 1998 through 2005 on a scatter diagram using Sales as the independent variable and Net Profit as the dependent variable.
(b) Draw the regression line on the graph you constructed in Part (a).
(c) What is the value of the coefficient of determination for this regression model? Comment on the strength of the regression line for this model.
(d) What is the predicted net profit for 2006 if sales are expected to be 75?