A custom-made product is produced by processing materially sequentially through four departments. To process material, department #1 requires .5 hours per unit, department #2 requires .6 hours per unit, department #3 requires .2 hours per unit, and department #4 requires .5 hours per unit.

if the original order is processed in three batches of 100 units each, how many hours will pass before all 300 units are completed and ready for shipment?