Determine the size mоdificаtiоn fаctоr, ψs, for а rectangular beam with b = 17 in. and d = 21 in., five uncoated No. 7 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 4 Grade 40 stirrups located every 10 in. along the span. Assume 8,000-psi lightweight concrete and a clear cover of 1.75 in.