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

Error probabilities and power

AP.STATS: UNC‑5 (EU), UNC‑5.B (LO), UNC‑5.B.1 (EK), UNC‑5.C (LO), UNC‑5.C.1 (EK)


Asha owns a car wash and is trying to decide whether or not to purchase a vending machine so customers can buy coffee while they wait. She'll get the machine if she's convinced that more than 30, percent of her customers would buy coffee. She plans on taking a random sample of n customers and asking them whether or not they would buy coffee from the machine, and she'll then do a significance test using alpha, equals, 0, point, 05 to see if the sample proportion who say "yes" is significantly greater than 30, percent.
Which situation below would result in the highest power for her test?
Choose 1 answer: