最近刚刚学习，有很多地方都不懂，然后遇到了下面两道题，问一下应该怎样做？希望好心人帮忙解惑
1.Suppose a sample of n = 25 items is drawn from a population described by a Normal distribution with standard deviation σ = 15, and that the sample mean of the 25 values is 96.4. Derive a 95%  onfidence interval for μ, the (unknown) mean of this distribution, and use your confidence interval to test, at the 5% significance level, the hypothesis H0 : μ = 100 against the general (two-sided)  lternative H1 : μ
= 100.
2. Outline the changes to all calculations in Q1 if, instead of knowing σ = 15, we have to estimate this quantity from the sample data, and our estimate is
s = 17.
Repeat the test of the hypothesis in Q1, and decide whether your conclusions change in these circumstances
3. Illustrate the p-values for the above hypothesis (with σ known or not), using sketches based on the appropriate reference distribution. Calculate the p-values associated with the tests outlined in Q1 and Q2.
这三道题是一起的，我有些地方连不起来，希望学长学姐们能帮帮忙，告诉一下应该怎么做