MATH 399N Week 6 MyStatLab Homework Solutions: Section 6.1, 6.3
1. Question: 6.1.3 For the same sample statistics, which level of confidence would produce the widest confidence interval? Explain your reasoning.
2. Question: 6.1.21 Construct the confidence interval for the population mean μ.
c = 0.95, x = 16.4, σ = 4.0, and n = 75
3. Question: 6.1.29 Find the minimum sample size n needed to estimate μ for the given values of c, σ, and E.
c = 0.90, σ = 6.8, and E = 1
4. Question: 6.1.47 People were polled on how many books they read the previous year. How many subjects are … to estimate the number of books read previous year within one book with 99 % …? Initial survey results indicate that σ = 16.3 books.
5. Question: 6.1.49 A doctor wants to estimate the HDL cholesterol of all 20-to-29-year –old females. How many subjects are … to estimate the HDL cholesterol within 4 points with 99 % confidence assuming σ = 18.2? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size required?
6. Question: 6.3.13 In a survey of 2630 adults, 1422 say they have started paying bills online in the last year.
Construct a 99% confidence interval for the population proportion. Interpret the results. S
7. Question: 6.3.15 In a survey of 8000 women, 5431 say they change their nail polish once a week. Construct a 99% confidence interval for the population proportion of women who change their nail polish once a week.
8. Question: 6.3.19-T A researcher wishes to estimate, with 99% confidence, the population proportion of adults who are confident with their country’s banking system. His estimate must be accurate within 2% of the population proportion.
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9. Question: 6.3.20-T A researcher wishes to estimate, with 90% confidence, the population proportion of adults who say chocolate is their favorite ice cream flavor. Her estimate must be accurate within 3% of the population proportion.
- No preliminary estimate is available. Find the minimum sample size needed.
- Find the minimum sample size needed. Using a prior study that found that 44% of the respondents said their favorite flavor of ice cream is chocolate.
- Compare the results form parts (a) and (b)
10. Question: 6.3.21 The table to the right shows the results of a survey in which 2554 adults from Country A, 1138 adults from Country B, and 1084 adults from Country C were asked if human activity contributes to global warming. Complete parts (a) and (c).
11. Question: 6.3.23-T The table shows the results of a survey in which separate samples of 400 adults each form the East, South, Midwest, and West were asked if traffic congestion is a serious problem in their community. Complete parts (a) and (b).
