Statistical Analysis Homework: Hypothesis Testing and Confidence Intervals, Assignments of Statistics

Download Statistical Analysis Homework: Hypothesis Testing and Confidence Intervals and more Assignments Statistics in PDF only on Docsity! Homework 6 1. Tires manufactured by company X are designed to have a mean of at least 28,000 miles and a population standard deviation of 1000 miles. Tests with 30 tires show a sample mean of 27,500 miles. Using 0.05 level of significance, test whether or not there is sufficient evidence to reject the claim of a mean of at least 28,000 miles. 2. Find an 80% confidence interval for the mean miles of a tire. 3. The U.S. Bureau of the Census reported mean hourly earnings in the wholesale trade industry of $9.70 per hour with a standard deviation of $1.05. A sample of 49 wholesale trade workers from Blacksburg, VA. The average for the sample was found to be $7.92. At = .10, is Blacksburg following the national average. 4. Use question #3 at  = 0.05 5. In the past, the Dumont Clothing Store has recorded 72% charge purchases and 28% cash purchases. A sample of 200 recent purchases shows that 160 were charge purchases. Does this suggest a change in the charge purchases? Write out the Hypothesis and give your answer. 6. Find a 99% confidence interval for the cash purchases in problem #5 7. A survey firm conducts door-to-door surveys on a variety of issues. Some individuals cooperate with the interviewer and complete the interview questionnaire, while others do not. The sample data are shown below: Respondents Sample Size Number Cooperating Men 200 110 Women 300 210 Using = 0.05 test the hypothesis that the response rate is the same for both populations of men and women. 8. Compute the 90% Confidence interval for the difference between the population proportions of women and men who cooperated with the survey.