In a certain city, there are 10,000 persons age 18 to 24. A simple random sample of

Question

500 such persons is drawn, of whom 200 turn out to be currently enrolled in college. Find a 90%
con¯dence interval for the percentage of persons age 18 to 24 in the city who are attending college.

Answer 1

Try using a binomial proportion CI formula:

CI90 = p + or - 1.645(√pq/n)
...where p = proportion in the problem, q = 1 - p, n = sample size, √ = square root, and + or - 1.645 represents 90% CI using a z-table.

Your data:
p = 200/500
q = 1 - p
n = 500

Convert all fractions to decimals. Substitute values into the formula and determine the confidence interval.

I hope this will help get you started.

Answer 2

500.12