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 .07days of the true mean number of days per month for which Los Angeles, CA fails to meet air-quality standards.