Exam 7: Confidence Intervals and Sample Size

A food snack manufacturer samples 9 bags of pretzels off the assembly line and weighed their contents.If the sample mean is 9.6 and the sample standard deviation is 0.20, find the 95% confidence interval of the True mean.

What is the value for for a 95% confidence interval when n = 18?

8 squirrels were found to have an average weight of 10.5 ounces with a sample standard deviation is 0.30. Find the 95% confidence interval of the true mean weight.

What is the 90% confidence interval for the variance of exam scores for 28 algebra students, if the standard deviation of their last exam was 12.7?

A college believes that 28% of applicants to that school have parents who have remarried.How large a sample is needed to estimate the true proportion of students who have parents who have remarried to Within 3% with 95% confidence?

The winning team's scores in 9 high school basketball games were recorded.If the sample mean is 10.5 points and the sample standard deviation is 0.15 points, find the 98% confidence interval of the true Mean.

An interval estimate may or may not contain the value of the parameter being estimated.

A chi-square variable cannot be negative, and the distributions are positively skewed.

A lawyer researched the average number of years served by 45 different judges on the Supreme Court. The average number of years served was 13.8 years with a standard deviation of 7.3 years.What is the 95% confidence interval for the average number of years served by all Supreme Court judges?

A report states that 46% of home owners had a vegetable garden.How large a sample is needed to estimate the true proportion of home owners who have vegetable gardens to within 5% with 95% Confidence?

The formula for the confidence interval of the mean for a specific α is __________.

A study of peach trees showed that the average number of peaches per tree was 1000.The standard deviation of the population is 150.A scientist wishes to find the 98% confidence interval for the mean Number of peaches per tree.How many trees does she need to sample to be accurate within 20 peaches Per tree?

A random sample of 95 printers discovered that 25 of them were being used in small businesses.Find the 99% limit for the population proportion of printers that are used in small businesses.

The width of a confidence interval for a population variance is of constant width for fixed values of the sample size and confidence level.