A work sampling study was performed on the day-shift maintenance department in a power generating station. The day-shift consists of four repair persons, each of whom works independently to repair equipment when it breaks down. A total of 800 observations (200 observations per repair person) were taken during a fourweek period (160 total hours of station operation). The observations were classified into one of the following categories: (1) maintenance person repairing equipment, or (2) maintenance person idle. There were a total of 432 observations in category 1. It is known that 83 equipment repairs were made during the 4 weeks. (a) How many more observations would be required, if any, to be 90% confident that the true proportion of category 1 activity is within 0.03 of the proportion indicated by the observations? Also, determine: (b) average time it takes a repair person to repair a piece of broken-down equipment, and (c) how many hours of idle time per week is experienced by each repair person, on average.

Part C needed.