Proceed with the same data summaries as before. A sample of n = 25 drivers was selected for a study of their car insurance policy premium. Individual records, {Xj : 1 j 25} are assumed to be independent and normally distributed with unknown parameters, (, ).

Sample summaries were reported as dollar amounts shown below:

X = SampleMean =82.80 and s= SampleSD =20

1. Estimate the unknown population mean = with confidence C = 0.95 = 95%

2. Show critical value, midpoint, and margin of error.

answer to previous question:

1. Ho : Mu=90 vs Hi : mu < 90

TS= -1.80

CV=-1.711

Reject Ho, enough evidence to conclude pop mean is below 90

2. Ho : Mu = 75 vs Hi : Mu >75

TS= 1.95

CV=1.711

Reject Ho, enough evidence to conclude pop mean is above 75

3. Ho : Mu = 75 vs Hi : Mu Does not = 75

TS= 1.95

CV= + or - 2.064

Do not reject Ho, not enough evidence to conclude pop mean differs