A submarine is a watercraft which capable of independent operation unden'u'ater. For generals submersion or surfacing, submarines use the forward and aft tanks, which are filled with water to submerge or with air to surface. When submerged, the water pressure on a submarine's hull on average can reach 580 psi with a standard deviation of 17 psi for steel submarines. Assume that the water pressure in submarine's hull is normally distributed