A factory has received an order for a product. It takes 9 operations to manufacture it. These may take place in any order and at any time in the manufacturing process but an individual worker stays with one operation from its beginning to its end. The number of hours for one worker to complete each operation is as follows:
All workers are able to complete all operations, but can only do one at a time. The product has to be ready in 16 hours.
What is the minimum number of workers required to manufacture the product in the given time?