If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Sample size and margin of error in a confidence interval for a mean

You might need: Calculator,Z table

Problem

Jeremiah wants to estimate the mean age of students at his large university. He'll sample n students and make a 95% confidence interval for the mean age. He is willing to use σ=3 years as an estimate of the standard deviation, and he wants the margin of error to be no more than 1 year.
Which of these is the smallest approximate sample size required to obtain the desired margin of error?
Choose 1 answer: