Families USA , a monthly magazine that discusses issues related to health and he
ID: 3149565 • Letter: F
Question
Families USA, a monthly magazine that discusses issues related to health and health costs, surveyed 21 of its subscribers. It found that the annual health insurance premiums for a family with coverage through an employer averaged $11,100. The standard deviation of the sample was $955. (Use t Distribution Table.)
Based on this sample information, develop a 95% confidence interval for the population mean yearly premium. (Round your answers to the nearest whole number.)
How large a sample is needed to find the population mean within $235 at 98% confidence? (Round up your answer to the next whole number.)
a.Based on this sample information, develop a 95% confidence interval for the population mean yearly premium. (Round your answers to the nearest whole number.)
Explanation / Answer
a) The 95% c.i=Xbar+-t(S/sqrt n)=11100+-2.086(955/sqrt21)=11100+-434.718=10665.282 to 11534.718, t critical at 20df and alpha=0.05 is 2.086.
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