A work sampling study was conducted to determine the proportion of the time a worker is idle. The following information was gathered on a random basis Number of Times Worker Idle Total Number of Observations 11 Day Monday Tuesday Wednesday Thursday 18 6 17 40 58 41 51 a. Based on these preliminary results, what percent of the time is the worker working? The worker is working 0 % of the time. (Enter your response rounded to two decimal places.) b. If idle time is judged to be excessive, what additional categories might you add to a follow-up work sampling study to identify the root causes? (Mark all that apply.) A. Quality assurance B. Number of workers C. Equipment failures D. Waiting for a customer order