A hollow shaft of 1 m length is designed to transmit a power of 30 kW at 700 rpm. The maximum permissible angle of twist in the shaft is 1o. The inner diameter of the shaft is 0.7 times the outer diameter. The modulus of rigidity is 80 GPa. The outside diameter (in mm) of the shaft is _______.
(a) 43 to 45
(b) 50to 60
(c) 70 to 80
(d) 85 to 100
(a) 43 to 45
(b) 50to 60
(c) 70 to 80
(d) 85 to 100