$4\mathrm{.}1$ The estimate for a five$-$story office building included $72$ doors on each of the upper three floors. In developing the bid, the estimator used a production rate of $2\mathrm{.}0$ carpenter man$-$hours to hang a door. The project superintendent is organizing the carpenter crews to include three carpenters per crew. What is the duration $($in days$)$ of the activity to hang all the doors on the upper three floors? Assume an $8-$hr workday.