A.hollow short cast-iron column has outside and inside diameters of 250 mm and 150 mm respectively. The column is subjected to an axial load applied at a distance 60 mm from the centre of the section. (a) Calculate the maximum safe load if the allowable stresses are 100 MPa compressive and 20 MPa tensile; and (b) plot a stress distribution diagram and calculate the position of the NA.