A cylindrical specimen of steel having an original diameter of 12.8mm(0.505 in.) is tensile tested to fracture and found to have an engineering fracture strength sf of 460 MPa (67,000 psi). If its cross-sectional diameter at fracture is 10.7 mm (0.422 in.), determine:

(a) The ductility in terms of percent reduction in area

(b) The true stress at fracture