The standard deviation for a population is =14.8. A sample of 19 observations selected from this population gave a mean equal to 137.80. The population is known to have a normal distribution. Round your answers to two decimal places. a. Make a 99% confidence interval for . b. Construct a 97% confidence interval for . c. Determine a 95% confidence interval for . d. Does the width of the confidence intervals constructed in parts a through c decrease as the confidence level decreases?.