Question Completion Status: QUESTION 2 When calculating the confidence interval, decreasing the confidence level will give you: a. A wider interval O b. A narrower interval O c. A larger standard deviation O d. A smaller standard deviation QUESTION 3 A sample of 10 observations is selected from a normal population for which the population standard deviation is known to be 5. The sample mean is 20. Round your answers to two decimal places. a) Determine the standard error of the mean. b) Determine the 95% confidence interval for the population mean. to QUESTION 4