The foreman in the welding department wanted to know what value of allowance to use for a particular section of the shop. A work sampling study was authorized. Only two activity categories were considered: (1) welding and other productive work, (2) personal time, rest breaks and delays. Over a four-week period, where there are 40 hours per week, 161 observations are made at random times. Each observation captured the category of activity of each of 12 welders in the shop section of interest. Results indicated that category 2 constituted 17 % of the total observations.

(a) Can you conclude that realized PFD is 17 % in the factory at 100*(1-0.02) % confidence level with 7% precision?

(b) If a total of 88 work units were produced during the 4 weeks, and all category 1 activity was devoted to producing these units, what was the average time spent on each unit?