Question
In a certain city, there are 10,000 persons age 18 to 24. A simple random sample of
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.
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.
Answers
MathGuru
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.
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.
Ashley
500.12