Marjorie is a trusted employee whose productivity declines as she works more and more hours each day. After careful observation of her work performance, her manager prepared the following chart. Listed first is the daily number of hours worked by Marjorie, and listed second is the total numbers of work units completed (for example, 4/340 means that four hours of work produces 340 completed work units). 0/0 1/100 2/190 3/270 4/340 5/400 6/450 For how many hours should the firm hire Marjorie to work each day if Marjorie's total cost to the firm is $11 per hour, and each work unit completed is worth $0.21 to the firm? 3 hours O4 hours O 6 hours 0 2 hours O 5 hours