Solution to Problem 4 Suppose you want to construct a 90% confidence interval for the proportion of college students that want to work in the health care profession after graduation. If you want a margin of error of no more than 5%, how many college students must you survey? Solution Since there is no preliminary estimate for the population proportion, we use the formula: We have: E = 0.05 c = 0.90 z_{c} = 1.645 Plug these numbers into the formula to get:We always round up, so we can conclude that we must survey 271 college students.
