Quiz on the demographic Transition

Today in class we took a quiz on the demographic transition.  I fell like I did fairly well on it, but I think I got the question on the equation incorrect.  I think that a wrote the incorrect equation.  then on the part of the quiz that asked what moved many countries to stage 2 in the late 19th century, I put the medical revolution because I thought that I had heard that somewhere, but I am not sure that that I correct.  Other than those two questions I feel like I did fairly well on this quiz.  I think that I got most of the rest of the questions on the rest of the quiz correct.