Problem:

Design fluorescent lighting for an area ${100}^{\text{'}}{40}^{\text{'}}$ with ${13}^{\text{'}}$ ceiling and $3^{\text{'}}$ workstation height where rough grinding of parts is performed. Fluorescent fixtures are to be flushed with ceiling with a cleaning schedule of every $24$ months. Ceiling and walls are painted white. Use $4^{\text{'}}$ long, $40$ watts fluorescent lamps in an uncovered fixture. $2$ lamps per fixture.