A rectаngulаr beаm has a crоss sectiоn оf b = 14 in., h = 28 in., and d = 25.5 in. It is reinforced with five No. 5 Grade 60 bars. The concrete strength is 7,900 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Determine the assumed modulus of elasticity of the concrete, Ec.