Livermore Industries uses a kanban system to manage production of the KR$-9$ subassembly. In a ten$-$hour day, they use $4600$ units and use containers that can hold $80$ units each. It takes $70$ minutes to fill and move a container of parts to the right place on the KR$-9$ line that is currently rated at a $\backslash (15\backslash \%\backslash )$ safety factor. How many production hours are needed?