Hemispherical end caps are welded to a cylindrical main body to form a propane storage tank. The tank has an inside diameter of d_i = 40 in. and is to be subjected to a maximum internal pressure of p = 120 psi. The allowable tensile stress in the wall of the tank is 12 ksi, and the allowable tensile stress in the weld is 8 ksi. (a) Determine the minimum wall thickness t_c of the cylindrical part of the tank. (b) Determine the minimum wall thickness t_sof the hemispherical end caps. (c) What is the minimum thickness of the weld?