2. A sample of 43 randomly selected months shows that the mean number of days per month for which Los Angeles, CA fails to meet air-quality standards is 5.42 with a population standard deviation of...

Extracted text: 2. A sample of 43 randomly selected months shows that the mean number of days per month for which Los Angeles, CA fails to meet air-quality standards is 5.42 with a population standard deviation of .93 days per month. a) Find a 99% confidence interval for the mean number of days per month for which Los Angeles, CA fails to meet air-quality standards. Explain the meaning in the context of the problem. b) Find the minimum sample size needed to be 99% confident that the sample mean is within .07 days of the true mean number of days per month for which Los Angeles, CA fails to meet air-quality standards.