please explain me
1. The 3 ways to test a hypothesis is by finding the critical value, finding a p-value or finidng a cofidence interval. Is that what is meant by the question?
2. $\displaystyle 1-\alpha$
3. Construct an interval and you will see it is the middle.
4. When $\displaystyle \sigma$ is unknown
5. I think you need more information to determine the null and alternate hypothesis here.