The following data are the monthly dollar amounts for landline telephone service for a random sample of 8 households in your community.

$43

$47

$51

$36

$50

$42

$38

$41

Find a 95% confidence interval for , the average monthly expenditure for landline telephone service.

For 95% confidence interval, the t-statistic from the distribution critical values is 2.365.

Find the sample mean

Find the standard deviation

Find the standard error SE

Find the Margin of error

95% confidence interval is

While answering the following questions, please make sure that you identify the value of t-statistic and show your calculations.

Why do we use t-statistic in this example and not the z-score?

Find the 80% confidence interval for the population mean

Find the 90% confidence interval for the population mean

Find the 95% confidence interval for the population mean

Find the 99% confidence interval for the population mean

Find the 99.9% confidence interval for the population mean

Describe how will you select a random sample of eight households (in the above problem).