A university is considering the proposal of a new policy. Not only is it

important that the policy has widespread support, the university wants to

have a good understanding of the difference in support between the teaching

staff and the non-teaching staff. It is proposed that n teaching staff and n

non-teaching staff are randomly selected and asked whether they support the

new policy. Determine n so that the length of the 95% confidence interval

for the difference in the percentage support between teaching staff and non-teaching

staff is at most 5%.