Reference no: EM1313713
Q1) Families USA, monthly magazine which describes issues related to health and health costs, surveyed 20 of its subscribers. It determined that annual health insurance premiums for family with coverage through the employer averaged $10,979. Standard deviation of sample was $1,000.
How large a sample is needed to find the population mean within $250 at 99 percent confidence?
Based on this sample information, create a 90% confidence interval for population mean yearly premium.
Q2) Mean amount bought by a typical customer at Churchill's Grocery Store is= $23.50 with a standard deviation of= $5.00. Suppose distribution of amounts purchased follows normal distribution. For sample of 50 customers, reply the following questions.
a) Determine the likelihood the sample mean is at least $25.00?
b) Determine the likelihood the sample mean is greater than $22.50 but less than $25.00?
c) Within what limits will 90% of sample means occur?