A rubber ball is inflated to a pressure of 65 kPa .At that pressure the diameter of the ball is 240mm and the wall thickness is 1.25 mm.The rubber has a modulus of elasticity E of 3.6 Mpa and a poisoon'd ratio of 0.48. Determine the maximum stress and strain in the ball. If the strain must br limited to 0.425,find the minimum wall thickness of the ball.