A cylinder of inner radius a and outer radius na, where n is an integer, has been design...

A cylinder of inner radius a and outer radius na, where n is an integer, has been designed to resist a specific internal pressure, but reboring becomes necessary. (a) Find the new inner radius r_x required so that the maximum tangential stress does not exceed the previous value by more than while the internal pressure is the same as before. (b) If a=25mm and n=2 and after reboring the tangential stress is increased by 10%, determine the new diameter.