Essentials Of Statistics For Business & Economics
9th Edition
ISBN: 9780357045435
Author: David R. Anderson, Dennis J. Sweeney, Thomas A. Williams, Jeffrey D. Camm, James J. Cochran
Publisher: South-Western College Pub
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Textbook Question
Chapter 6.2, Problem 20E
Gasoline Prices. Suppose that the average price for a gallon of gasoline in the United States is $3.73 and in Russia is $3.40. Assume these averages are the population means in the two countries and that the
- a. What is the probability that a randomly selected gas station in the United States charges less than $3.50 per gallon?
- b. What percentage of the gas stations in Russia charge less than $3.50 per gallon?
- c. What is the probability that a randomly selected gas station in Russia charged more than the
mean price in the United States?
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Question 4
An article in Quality Progress (May 2011, pp. 42-48) describes the use of factorial experiments to improve a
silver powder production process. This product is used in conductive pastes to manufacture a wide variety of
products ranging from silicon wafers to elastic membrane switches. Powder density (g/cm²) and surface area
(cm/g) are the two critical characteristics of this product. The experiments involved three factors: reaction
temperature, ammonium percentage, stirring rate. Each of these factors had two levels, and the design was
replicated twice. The design is shown in Table 3.
A222222222222233
Stir Rate
(RPM)
Ammonium
(%)
Table 3: Silver Powder Experiment from Exercise 13.23
Temperature
(°C)
Density
Surface Area
100
8
14.68
0.40
100
8
15.18
0.43
30
100
8
15.12
0.42
30
100
17.48
0.41
150
7.54
0.69
150
8
6.66
0.67
30
150
8
12.46
0.52
30
150
8
12.62
0.36
100
40
10.95
0.58
100
40
17.68
0.43
30
100
40
12.65
0.57
30
100
40
15.96
0.54
150
40
8.03
0.68
150
40
8.84
0.75
30
150…
-
+
++
Table 2: Crack Experiment for Exercise 2
A B C D Treatment Combination
(1)
Replicate
I II
7.037
6.376
14.707 15.219
|++++ 1
བྱ॰༤༠སྦྱོ སྦྱོཋཏྟཱུ
a
b
ab
11.635 12.089
17.273 17.815
с
ас
10.403 10.151
4.368 4.098
bc
abc
9.360 9.253
13.440 12.923
d
8.561 8.951
ad
16.867 17.052
bd
13.876 13.658
abd
19.824 19.639
cd
11.846 12.337
acd
6.125
5.904
bcd
11.190 10.935
abcd
15.653 15.053
Question 3
Continuation of Exercise 2. One of the variables in the experiment described in Exercise 2, heat treatment
method (C), is a categorical variable. Assume that the remaining factors are continuous.
(a) Write two regression models for predicting crack length, one for each level of the heat treatment method
variable. What differences, if any, do you notice in these two equations?
(b) Generate appropriate response surface contour plots for the two regression models in part (a).
(c) What set of conditions would you recommend for the factors A, B, and D if you use heat treatment method
C = +?
(d) Repeat…
Question 2
A nickel-titanium alloy is used to make components for jet turbine aircraft engines. Cracking is a potentially
serious problem in the final part because it can lead to nonrecoverable failure. A test is run at the parts producer
to determine the effect of four factors on cracks. The four factors are: pouring temperature (A), titanium content
(B), heat treatment method (C), amount of grain refiner used (D). Two replicates of a 24 design are run, and
the length of crack (in mm x10-2) induced in a sample coupon subjected to a standard test is measured. The
data are shown in Table 2.
1
(a) Estimate the factor effects. Which factor effects appear to be large?
(b) Conduct an analysis of variance. Do any of the factors affect cracking? Use a = 0.05.
(c) Write down a regression model that can be used to predict crack length as a function of the significant
main effects and interactions you have identified in part (b).
(d) Analyze the residuals from this experiment.
(e) Is there an…
Chapter 6 Solutions
Essentials Of Statistics For Business & Economics
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Ch. 6.2 - Given that z is a standard normal random variable,...Ch. 6.2 - Given that z is a standard normal random variable,...Ch. 6.2 - 13. Given that z is a standard normal random...Ch. 6.2 - Given that z is a standard normal random variable,...Ch. 6.2 - Given that z is a standard normal random variable,...Ch. 6.2 - Given that z is a standard normal random variable,...Ch. 6.2 - Height of Dutch Men. Males in the Netherlands are...Ch. 6.2 - Large-Cap Domestic Stock Fund. The average return...Ch. 6.2 - Automobile Repair Costs. Automobile repair costs...Ch. 6.2 - Gasoline Prices. Suppose that the average price...Ch. 6.2 - Mensa Membership. A person must score in the upper...Ch. 6.2 - Television Viewing. Suppose that the mean daily...Ch. 6.2 - Time to Complete Final Exam. The time needed to...Ch. 6.2 - Labor Day Travel Costs. The American Automobile...Ch. 6.2 - Household Income in Maryland. According to Money...Ch. 6.3 - A binomial probability distribution has p=.20 and...Ch. 6.3 - Assume a binomial probability distribution has p =...Ch. 6.3 - Adults Who Smoke. Although studies continue to...Ch. 6.3 - Americans Who Believe Global Warming Is Occurring....Ch. 6.3 - Playing Video Games. Suppose that of those...Ch. 6.3 - Visitors to Rocky Mountain National Park. Rocky...Ch. 6.4 - Consider the following exponential probability...Ch. 6.4 - 33. Consider the following exponential probability...Ch. 6.4 - 34. Battery life between charges for the Motorola...Ch. 6.4 - 35. The time between arrivals of vehicles at a...Ch. 6.4 - 36. Comcast Corporation is the largest cable...Ch. 6.4 - 37. Wendy’s restaurant has been recognized for...Ch. 6.4 - 38. The Boston Fire Department receives 911 calls...Ch. 6 - 39. A business executive, transferred from Chicago...Ch. 6 - NCAA Scholarships. The NCAA estimates that the...Ch. 6 - Production Defects. Motorola used the normal...Ch. 6 - Bringing Items to a Pawnshop. One indicator of the...Ch. 6 - Amazon Alexa App Downloads. Alexa is the popular...Ch. 6 - Service Contract Offer. Ward Doering Auto Sales is...Ch. 6 - Wedding Costs. The XO Group Inc. conducted a 2015...Ch. 6 - College Admissions Test Scores. Assume that the...Ch. 6 - College Graduates Starting Salaries. According to...Ch. 6 - 48. A machine fills containers with a particular...Ch. 6 - Multiple-Choice Exam. Consider a multiple-choice...Ch. 6 - Playing Blackjack. A blackjack player at a Las...Ch. 6 - Mean Time Between Failures. The mean time between...Ch. 6 - The website for the Bed and Breakfast Inns of...Ch. 6 - Do you dislike waiting in line? Supermarket chain...Ch. 6 - Prob. 54SE
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- A 24-1 design has been used to investigate the effect of four factors on the resistivity of a silicon wafer. The data from this experiment are shown in Table 4. Table 4: Resistivity Experiment for Exercise 5 Run A B с D Resistivity 1 23 2 3 4 5 6 7 8 9 10 11 12 I+I+I+I+Oooo 0 0 ||++TI++o000 33.2 4.6 31.2 9.6 40.6 162.4 39.4 158.6 63.4 62.6 58.7 0 0 60.9 3 (a) Estimate the factor effects. Plot the effect estimates on a normal probability scale. (b) Identify a tentative model for this process. Fit the model and test for curvature. (c) Plot the residuals from the model in part (b) versus the predicted resistivity. Is there any indication on this plot of model inadequacy? (d) Construct a normal probability plot of the residuals. Is there any reason to doubt the validity of the normality assumption?arrow_forwardStem1: 1,4 Stem 2: 2,4,8 Stem3: 2,4 Stem4: 0,1,6,8 Stem5: 0,1,2,3,9 Stem 6: 2,2 What’s the Min,Q1, Med,Q3,Max?arrow_forwardAre the t-statistics here greater than 1.96? What do you conclude? colgPA= 1.39+0.412 hsGPA (.33) (0.094) Find the P valuearrow_forward
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