Thank you for the opportunity to help you with your question!
It is a right tailed test ( so only one critical value - to the right of the mean)
- and it is a T test because n is less than 30....
so using degrees of freedom 8 (which is n-1)
and alpha = 0.01
use your T table to look up your critical value (the answer will be positive)
Using α = 0.05 for a left-tailed test, find the critical z value used to test the null hypothesis. –1.645; +/–1.96; +/–1.645 ... the critical value or values of χ2based on the given information. H1: σ > 26.1, n = 9, α = 0.01. gives 20.090; 21.666; 1.646 ...
Please let me know if you need any clarification. I'm always happy to answer your questions.