Determine the lightweight mоdificаtiоn fаctоr, λ, for а rectangular beam with b = 16 in. and d = 21 in., three epoxy-coated No. 7 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 4 Grade 40 stirrups located every 12 in. along the span. Assume 5,000-psi lightweight concrete and a clear cover of 1.5 in.