Inferences About Means and Proportions

ISDS 361B

HOME WORK 2

INFERENCES ABOUT MEANS AND PROPORTIONS

FOR TWO POPULATIONS

USE EXCEL TO DO ALL QUESTIONS

1)  The international Air Transportation Association surveyed business travelers to determine ratings of various international airports. The maximum possible rating score was 10. Suppose 50 business travelers were asked to rate the Miami airport, and 50 other business travelers were asked to rate the Los Angeles airport. The rating scores are stored in Question 1 – Data.

a)  Assuming standard deviations of Miami ratings and Los Angeles ratings are known as s12 = 2.2 and s22 = 2.4, develop a 95% confidence interval estimate of the difference between the mean ratings of the Miami and Los Angeles airport.

b)  How many travelers in Miami and Los Angeles should be surveyed to estimate the true average difference in rating to within ±0.5?

c)  Assuming standard deviations of Miami rating and Los Angeles ratings are not known; develop a 95% confidence interval estimate of the difference between the mean ratings of the Miami and Los Angeles airport.

2)  KELLER Book, Page 456, Question 13.1

3)  KELLER Book, Page 457, Question 13.2

4)  KELLER Book, Page 457, Question 13.3a

5)  KELLER Book, Page 457, Question 13.4a

6)  KELLER Book, Page 458, Question 13.11a & b

7)  KELLER Book, Page 459, Question 13.19a & b

8)  KELLER Book, Page 460, Question 13.25

9)  KELLER Book, Page 460, Question 13.28

10) KELLER Book, Page 474, Question 13.40

11) KELLER Book, Page 475, Question 13.46

12) KELLER Book, Page 475, Question 13.48

a)  Do these data allow the contractor to infer at 5% significance level that the heating cost for insulated chouses is less than that for the uninsulated houses

b)  As stated on book

c)  Do these data allow the contractor to infer at 5% significance level that the heating cost for insulated chouses is less than that for the uninsulated houses by $50?

13) KELLER Book, Page 493, Question 13.67

a)  Calculate the value of the test statistic z

b)  Does these data allow you to conclude that P1≠P2 at 5% significance level?

c)  Repeat b), increasing sample size to 400

14) KELLER Book, Page 494, Question 13.69

a)  Estimate with 90% confidence the difference in population proportions

15) KELLER Book, Page 495, Question 13.77

16) KELLER Book, Page 496, Question 13.82 (Data File Xr13-82)

17) KELLER Book, Page 499, Question 13.89

18) KELLER Book, Page 499, Question 13.90

Homework 2 - Question 2