The Chief IE in the production department wanted to know what value of PFD allowance to use for a particular section of the shop. A work sampling study was authorized. Only three activity categories were considered: (1) production work, (2) personal time, rest breaks, and delays, and (3) other activities. Over a four week period (40 hours/week), 100 observations were made at random times. Each observation captured the category of activity of each of 22 production workers in the department. Results indicated that category 2 constituted 19% of the total observations. (a) Define the limits of a 95% confidence interval for activity 2. (b) If a total of 522 work units were produced during the 4 weeks, and the 1540 observations in category 1 activity were all devoted to producing these units, what was the average time spent on each unit?