# Question 1 – Exercise 8.3 Why is it not possible in Example 8.1 on page 256 to have 100% confidence? Explain. Answer If you have 100% confidence in the value of the calculated mean, then have the true...

Question 1 – Exercise 8.3Why is it not possible in Example 8.1 on page 256 to have 100% confidence? Explain.AnswerIf you have 100% confidence in the value of the calculated mean, then have the true population mean and the only way to have the true population mean is to use the entire population, which they did not do in Example 8.1.Question 2 – Exercise 8.19The file Sedans contains the overall miles per gallon (MPG) of 2009 sedans priced under \$20.000.
Document Preview:

Question 1 – Exercise 8.3Why is it not possible in Example 8.1 on page 256 to have 100% confidence? Explain.AnswerIf you have 100% confidence in the value of the calculated mean, then have the true population mean and the only way to have the true population mean is to use the entire population, which they did not do in Example 8.1.Question 2 – Exercise 8.19The file Sedans contains the overall miles per gallon (MPG) of 2009 sedans priced under \$20.000.27313028272429323227262625262524Source: Data extracted from “Vehicle Ratings,” Consumer Reports, April 2009, p. 27Construct a 95% confidence interval estimate for the population mean MPG of 2009 sedans (4-cylinder) priced under \$20.000, assuming a normal distribution.Interpret the interval constructed in (a).Compare the results in (a) to those in Problem 8.20 (a)Note: To answer Question 2 – Exercise 8.19 I did Question 2 – Exercise 8.20(a) offline.Question 2 – Exercise 8.19 is continued on the next page…Question 2 – Exercise 8.19 (Continued…)Answer: Part (a)Confidence Interval=x±t SEx=x±tsn=27.4375± XXXXXXXXXXConfidence Interval=27.4375±1.4160Confidence Interval is XXXXXXXXXX=µ=28.8535Answer: Part (b)I can be 95% confident that the true population mean of MPG of 2009 sedans (4-cylinder) priced under \$20,000 is between XXXXXXXXXXand XXXXXXXXXXassuming a normal distribution.Answer: Part (c)I can be 95% confident that the true population mean of MPG of 2009 small SUV’s is less than the true population mean of MPG of 2009 sedans (4-cylinder) priced under \$20,000 since the two confidence intervals do not overlap. Question 3 – Exercise 8.22One of the major measures of the quality of service provided by any organization is the speed with which t responds to customer complaints. A large family-held department store selling furniture and flooring, including carpet, had undergone a major expansion in the past several years. In particular, the flooring department had expanded from 2...

## Solution

Robert answered on Dec 31 2021
Question 1 – Exercise 8.3
Why is it not possible in Example 8.1 on page 256 to have 100% confidence? Explain.
If you have 100% confidence in the value of the calculated mean, then have the true population mean and
the only way to have the true population mean is to use the entire population, which they did not do in
Example 8.1.
Question 2 – Exercise 8.19
The file Sedans contains the overall miles per gallon (MPG) of 2009 sedans priced under \$20.000.
27 31 30 28 27 24 29 32 32 27 26 26 25 26 25 24
Source: Data extracted from “Vehicle Ratings,” Consumer Reports, April 2009, p. 27
a) Construct a 95% confidence interval estimate for the population mean MPG of 2009 sedans (4-
cylinder) priced under \$20.000, assuming a normal distribution.
) Interpret the interval constructed in (a).
c) Compare the results in (a) to those in Problem 8.20 (a)
Note: To answer Question 2 – Exercise 8.19 I did Question 2 – Exercise 8.20(a) offline.
Question 2 – Exercise 8.19 is continued on the next page…
Question 2 – Exercise 8.19 (Continued…)
(

) (

)
I can be 95% confident that the true population mean of MPG of 2009 sedans (4-cylinder) priced under
\$20,000 is between 26.0215 and 28.8535 assuming a normal distribution.