in a certain region 23 % of people over age 50 didnt graduate from high school . we would like to know if this percentage is the same among the 25-30 year age group use critical value upto 3 decimal places. (a) How many 25-30 year old people should be surveyed in order to estimate the proportion of non-grads to within 8% with 90% confidence? (b) Suppose we wanted to cut the margin of error to 6%. How many people should be sampled now? x (c) What sample size is required for a margin of error of 9% ?