"Calculate the initial diameter of a wire that has been longitudinally strained by 30% and whose final diameter is 0.1cm. Assume no volume change." Now I know that if there is no volume change, v=poisson's ratio= 0.5. Thus the lateral strain would equal 30%*0.5= 15%. But when I plug it into the strain equation and use a diameter of 0.1cm as the initial length, I get 0.1176. The answer is supposed to be 0.114cm. Any thoughts?