Refer to Exercise 16.

a. Find a \(95 \%\) lower confidence bound for the mean time.

b. Find a \(90 \%\) upper confidence bound for the mean time.

Data From Exercise 16:

The article "Application of Surgical Navigation to Total Hip Arthroplasty" (T. Ecker and S. Murphy, Journal of Engineering in Medicine, 2007: 699-712) reports that in a sample of 123 hip surgeries of a certain type, the average surgery time was 136.9 minutes with a standard deviation of 22.6 minutes.