Concept explainers
(a)
To find: the value of n.
(a)
Answer to Problem 8CRE
Explanation of Solution
Given:
90% confidence interval: (0.858, 0.942)
90% confidence interval: (0.109, 0.211)
Formula used:
Calculation:
The margin of error is
For confidence level
The sample size must be equal (due to rounding errors they are not equal) and therefore the sample size is most probable
(b)
To Explain: the reason for the interval is not a 95 percent confidence interval for the ratio of orders returned to consumers within 5 days of the shift.
(b)
Explanation of Solution
The interval was built in order to obtain an approximation of the population proportions difference. However, the two-sample z-test used the confidence interval of the population difference, and this is not the variation of the confidence intervals derived from the one-sample z-test
(c)
To construct: and explain a valid 95 % confidence interval to replace that set out in Part (b)
(c)
Answer to Problem 8CRE
(0.6612, 0.8188)
Explanation of Solution
Given:
Formula used:
The confidence interval endpoints for are then:
Calculation:
For confidence level
The confidence interval endpoints for are then
There is confidence in 95 percent that the real gap in population proportion is between 0.6612 and 0.8188.
Chapter 10 Solutions
The Practice of Statistics for AP - 4th Edition
Additional Math Textbook Solutions
An Introduction to Mathematical Statistics and Its Applications (6th Edition)
Introductory Statistics (2nd Edition)
Basic Business Statistics, Student Value Edition (13th Edition)
Essentials of Statistics (6th Edition)
Elementary Statistics: Picturing the World (7th Edition)
Introductory Statistics (10th Edition)
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