and a standard deviation=2.8 2.8.

a. Find a? 95% confidence interval for ?.

b. Find a? 90% confidence interval for ?.

c. Find a? 99% confidence interval for ?.

a. The? 95% confidence interval is

?(Use integers or decimals for any numbers in the expression. Round to two decimal places as? needed.)

b. The? 90% confidence interval is

?(Use integers or decimals for any numbers in the expression. Round to two decimal places as? needed.)

c. The? 99% confidence interval is

?(Use integers or decimals for any numbers in the expression. Round to two decimal places as? needed.)