Determine the minimum factor of safety for fatigue based on infinite life, using the modified Goodman criterion for a shaft that rotates at a constant speed, has a constant diameter of 30 mm, and is made from cold-drawn AISI 1018 steel. The critical stress element experiences oa = 60 MPa, Tm = 34 MPa, Om = 0, and Ta = 0. The minimum factor of safety for fatigue is)