Families USA, a monthly magazine that discusses issues related to health and health costs, surveyed 18 of its subscribers. It found that the annual health insurance premiums for a family with coverage through an employer averaged $10,350. The standard deviation of the sample was $1,025. (Uset Distribution Table.)

a. Based on this sample information, develop a 99% confidence interval for the population mean yearly premium. (Round your answers to the nearest whole dollar amount.)

b. How large a sample is needed to find the population mean within $245 at 99% confidence? (Round up your answer to the next whole number.)