The manager of Lawn and Garden Services would like to estimate the proportion of her employees' time spent performing various gardening and lawn care activities. She has made 400 random observations of a typical worker, with the following results: Activity Time Observed Mowing 200 Trimming 80 Raking 40 Miscellaneous 80 How confident can the manager be that the true proportion of time spent mowing is between 0.45 and 0.55