The analyst in the dorben reference library decides to use the work sampling technique to establish standards. twenty employees are involved. the operations include cataloging, charging books out, returning books to their proper location, cleaning books, record keeping, packing books for shipment, and handling correspondence. a preliminary investigation resulted in the estimate that 30 percent of the time of the group was spent in cataloging. how many work sampling observations would be made if it were desirable to be 95 percent confident that the observed data were within a tolerance of ±10 percent of the population data? describe how the random observations should be made.