Bishuiwan Hot Spring Swimming Pool has a cuboid swimming pool with a length of 50 meters, a width of 30 meters and a water depth of 1.8 meters. If the water is drained outward, 2.5 cubic meters per minute, how many hours can the water in the pool be taken?
碧水湾温泉游泳馆有一个长为50米，宽为30米，水深为1.8米的长方体游泳池，如果用水向外排水，每分排水2.5立方米，几小时可以把池内水拍完？
<result>18</result>