Thread: constructing a confidence interval

among 500 marriage license applications chosen at random, there were 48 in which the woman was at least 1 year older than the man, and among 400 marriage license applications chosen at random 6 years later, there were 68 in which the woman was at least 1 year older than the man. Construct a 99% confidence interval for the difference between the corresponding true proportions of marriage license applications in which the woman was at least 1 year older than the man.

Could use some assistance on this. Thank you for anyone who can help me.

where from http://bayes.bgsu.edu/nsf_web/jscrip...ormal_icdf.htm