If the corrected endurance strength is 70MPa, estimated shaft life will be

Question

A cylindrical shaft is subjected to an alternating stress of 100MPa. Fatigue strength to sustain 1000 cycles is 490MPa. If the corrected endurance strength is 70MPa, estimated shaft life will be

      (a) 1071 cycles                                                   (b) 15000 cycles

      (c) 281914 cycles                                               (d) 928643 cycles