suppose we wish to construct a confidence interval for a population proportion p. if we sample without replacement from a relatively small population of size N, the margin or error E is modified to include the finite population correction factor as follows:

Question

suppose we wish to construct a confidence interval for a population proportion p.  if we sample without replacement from a relatively small population of size N, the margin or error E is modified to include the finite population correction factor as follows: 
E=Za/2 pq/n    N-n/N-1

construct a 90% confidence interval for the porportion of students at a school who are left handed.  the numbers of students at the school is N=320.  in a random sample of 80 students, selected without replacement, there are 7 left handers.