A sample of 20 observations is selected from a normal population where the population standard deviation is 22. The sample mean is 62.

a. Determine the standard error of the mean.(Round the final answer to 3 decimal places.)

The standard error of the mean is.

b.Determine the 80% confidence interval for the population mean.(Round thez-value to 2 decimal places. Round the final answers to 3 decimal places.)

The 80% confidence interval for the population mean is betweenand.

c.If you wanted a wider interval, would you increase or decrease the confidence level?

Increase or decrease