A sample of 20 automobiles has a pollution by-product release standard deviation of 2.5 ounces when one gallon of gasoline is used. Find the 95% confidence interval of the population variance. using chi table determine the confidence interval of the true population variance

A random sample of 17 snowmobiles was selected, and the lifetime of the battery was measured. The variance of the sample was 9.7 months. Find the 95% confidence interval of the true variance. Please include all work showing how you found your answer.

The average length of stay of a sample of 20 patients discharged from a general hospital was 7 days with a standard deviation of 2 days. A sample of 22 patients discharged from a chronic disease hospital had an average length of stay of 36 days with a standard deviation of 10 days. Assume that you sampled from normally distributed populations with equal variances. Find the 90% confidence interval for the difference between the average length of hospital stays between these two populations. Use a pooled variance of 54.4. Round the value of your reliability coefficient to three decimal places.

A sample of size 50 from a normal distribution has sample mean 5 and sample variance 20. Find 96% confidence intervals for the variance and standard deviation of the distribution.