value: 10.00 points Families USA, a monthly magazine that discusses issues relat

Question

value: 10.00 points Families USA, a monthly magazine that discusses issues related to health and health costs, surveyed 22 of its subscribers. It found that the annual health insurance premiums for a family with coverage through an employer averaged $10,800. The standard deviation of the sample was $1,060. (Use t Distribution Table.) a. Based on this sample information, develop a 90% confidence interval for the population mean yearly premium. Round your answers to the nearest whole number and s Confidence interval for the population mean yearly premium is between b. How large a sample is needed to find the population mean within $240 at 90% confidence? (Round up your answer to the next whole number.) Sample size 53

Explanation / Answer

for std error=std deviation/(n)1/2 =225.9928

for 90% CI and 21 degree if freedom ; t=1.7207

a)hence confidence interval =mean +/- t*std error =10411 ; 11189

b)here E=240

std deviation =1060

for 90% CI, z=1.6449

hence sample size =(Z*std deviation/E)2 =53

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