The ratio $\frac{M_{t1}}{M_{t2}}$ is

Question

The outside diameter of a hollow shaft is twice that of its inside diameter. The torque – carrying capacity of this shaft is $M_{t1}$. Solid shaft of the same material has the diameter equal to the outside diameter of the hollow shaft. The solid shaft can carry a torque of $M_{t2}$ . The ratio $\frac{M_{t1}}{M_{t2}}$ is

(a) 15/16                         (b) 3/4

(c) 1/2                             (d) 1/16