In: Statistics and Probability
To approximate the proportion p of out-of-state students at University A, n samples are taken in a survey.
(1) Find the mean and standard deviation of sample proportion p̂.
(2) A survey shows that there are 23 out-of-state students out of 100 students. Find the 95% confidence interval for p.
(3) If we require the estimating error is less than 3% with 95% confidence, how many samples are required at least?
(4) Another sample shows that there are 10 out-of-state students out of 50 students from University B. Find the 95% confidence interval for the difference of two proportions between Universities A and B.