Uploaded November 2012 | Updated September 2026, 2 hours ago
I have an updated and improved version of this video available at: youtu.be/m6sGjWz2CPg
I work through a few quick examples of determining what area corresponds to the p-value in one-sample Z tests on the population mean mu. The same logic holds for other types of test. I assume that you know how to find areas under the standard normal curve.
I have an updated and improved version of this video available at: youtu.be/m6sGjWz2CPg
I work through a few quick examples of determining what area corresponds to the p-value in one-sample Z tests on the population mean mu. The same logic holds for other types of test. I assume that you know how to find areas under the standard normal curve.







![Confidence Intervals for One Mean: Sigma Not Known (t Method)
Introduction to confidence intervals for mu based on the t distribution. These methods are appropriate when we are sampling from a normally distributed population and the population standard deviation (sigma) is not known.
The cereal data used in this video is real data from a sample of 7 cereal boxes I purchased one day. The boxes had a stated weight of 750 grams. (Ive changed the story slightly in the video, but it is real data.)
For those that use R, below is the R code to find the values given in the video.
With 6 degrees of freedom, the t value with an area of 0.025 to the right (and thus an area of 0.975 to the left), can be found with:
qt(.975,6)
[1] 2.446912 Confidence Intervals for One Mean: Sigma Not Known (t Method)](https://i.ytimg.com/vi/bFefxSE5bmo/mqdefault.jpg)


