A business school dean is contemplating proposing a change in the requirements for graduation. At present, business majors are required to take one science course, chosen from a list of possible courses. The proposal is that this be replaced by the requirement that a course in ecology be taken. The business school has 420 students. In a random sample of 100 of these students, 56 expressed opposition to this proposal. Find a 90% confidence interval for the proportion of all the school's students opposed to the proposed change in requirements.