The Dulac Box plant produces 500 cypress packing boxes in two 10hour shifts. Due to higher demand, they have decided to operate three 8-hour shifts instead. They are now able to produce 600 boxes per day. What has happened to productivity? a. It has decreased by 9.1%. b. It has decreased by 8.3%. c. It has increased by 20%. d. It has increased by 37.5 boxes /hr. e. It has not changed