Beyond Common Core
Problem 35 of 45s12-035
A random sample of 50 commuters gives a 95% confidence interval of 22 to 28 minutes for the mean commute time in a city. What does "95% confident" mean here?
Try it first
The walkthrough opens once you check an answer.
Solution walkthrough1:28
- Picture taking many random samples of 50 commuters and building an interval from each, the same way.
- Each interval either contains the true mean or misses it. About 95% of them catch it.
- Our interval, 22 to 28 minutes, is one of these. The 95% describes the method, not a chance for this one interval.
- Traps: no 95% chance for one fixed interval, it is not about single commutes, and not about other sample means.