BUS 352 T8 Chapter 11 Homework Problems 2015

11.21 When performing a X?test of independence in a contingency table with r rows and c columns, determine the

upper-tail critical value of the test statistic in each of the following circumstances:

a. ? = 0.05, r = 4 rows, c = 5 columns

b. ? = 0.01, r = 4 rows, c = 5 columns

c. ? = 0.01, r = 4 rows, c = 6 columns

d. ? = 0.01, r = 3 rows, c = 6 columns

e. ? = 0.01, r = 6 rows, c = 3 columns

11.22 The owner of a restaurant serving Continental-style entrées has the business objective of learning more about

the patterns of patron demand during the Friday-to-Sunday weekend time period. Data were collected from 630

customers on the type of entrée ordered and the type of dessert ordered and organized into the following table:

TYPE OF TYPE OF ENTRÉE

DESSERT Beef Poultry Fish Pasta Total

Ice cream 13 8 12 14 47

Cake 98 12 29 6 145

Fruit 8 10 6 2 26

None 124 98 149 41 412

At the 0.05 level of significance, is there evidence of a relationship between type of dessert and type of entrée?

11.26 USA Today reported on when the decision of what to have for dinner is made. Suppose the results were

based on a survey of 1,000 respondents and considered whether the household included any children under 18

years old. The results are cross-classified in the following table:

TYPE OF HOUSEHOLD

WHEN DECISION

MADE

One Two or Two or

Adult/No More Adults/ More Adults/

Children Children No Children

Just before eating 162 54 154

In the afternoon 73 38 69

In the morning 59 58 53

A few days before 21 64 45

The night before 15 50 45

"Always eat the same 2 16 2

"

thing on this night

Not sure 7 6 7

At the 0.05 level of significance, is there evidence of a significant relationship between when the decision is made of what to have for dinner and the type of household?

12.3 Fitting a straight line to a set of data yields the following

prediction line:

?? = 16 - 0.5X?

a. Interpret the meaning of the Y intercept, b?

b. Interpret the meaning of the slope, b?

c. Predict the value of Y for X = 6.

12.7 Starbucks Coffee Co. uses a data-based approach to improving the quality and customer satisfaction of its products.

When survey data indicated that Starbucks needed to improve its package sealing process, an experiment was conducted (data

extracted from L. Johnson and S. Burrows, “For Starbucks, It’s In the Bag,” Quality Progress, March 2011, pp. 17–23) to determine

the factors in the bag-sealing equipment that might be affecting the ease of opening the bag without tearing the inner liner of the bag. One factor that could affect the rating of the ability of the bag to resist tears

ability of the bag to resist tears equipment. Data was collected on 19 bags in which the

plate gap was varied. The results are stored in Starbucks.

a. Construct a scatter plot.

b. Assuming a linear relationship, use the least-squares method to determine the regression coefficients b? and b?

c. Interpret the meaning of the slope, b? in this problem.

d. Predict the tear rating when the plate gap is equal to 0.

12.9 An agent for a residential real estate company has the business objective of developing more accurate estimates of

the monthly rental cost for apartments. Toward that goal, the agent would like to use the size of an apartment, as defined

by square footage to predict the monthly rental cost. The agent selects a sample of 25 apartments in a particular residential

neighborhood and collects the following data (stored in Rent).

a. Construct a scatter plot.

b. Use the least-squares method to determine the regression coefficients b? and b?

c. Interpret the meaning of b? and b? in this problem.

d. Predict the monthly rent for an apartment that has 1,000 square feet.

12.19 In Problem 12.7 on page 441, you used the plate gap on the bag-sealing equipment to predict the tear rating of a bag of coffee (stored in Starbucks). Using the results of that problem,

a. determine the coefficient of determination, and interpret its meaning.

b. determine the standard error of the estimate.

c. How useful do you think this regression model is for predicting the tear rating based on the plate gap in the bag-sealing equipment?

12.21 In Problem 12.9 on page 442, an agent for a real estate company wanted to predict the monthly rent for apartments, based on the size of the apartment (stored in Rent). Using the results of that problem,

a. determine the coefficient of determination, and interpret its meaning.

b. determine the standard error of the estimate.

c. How useful do you think this regression model is for predicting the monthly rent?

d. Can you think of other variables that might explain the variation in monthly rent?