A confidence interval for a mean estimates a based on a results from a sample. For example, if 70 adults own a cell phone in a random sample of 100 adults, we can be fairly confident that the true percentage in the population is somewhere between 61% and 79%. Go through this tutorial to learn how to calculate confidence intervals like this.
4632_Small_sample_size_confidence_intervals.html
All video content by Khan Academy is under their license: CC by NC SA
Website created using Khan Academy Static Downloader