A sample of 26 observations is selected from a normal population where the population standard deviation is 34. The sample mean is 80.

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 95% confidence interval for the population mean.(Round the z-value to 2 decimal places. Round the final answers to 3 decimal places.)

The 95% confidence interval for the population mean is between and .

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

(Click to select) Decrease Increase