A small steel rod is to be utilized as a part in a high-performance automobile engine. The rod is made from a new ultra-high strength alloy steel known as HO 9-4-20 (composition 9% Ni, 4% Co and 0.2% C), heat-treated by austenitizing, quenching ang tempering at 550C to give an ultimate tensile strength of 210 ksi. The rod must support in service a mean tensile stress of 60 ksi, but will also be subjected to an alternating stress (of roughly constant amplitude) superimposed on the mean stress. Allowing for a safety faction of 3, what would be your recommendation for the maximum allowable alternating stress that the rod could withstand to last 105 cycles