# Thread: Hypothesis Testing I think.

1. ## Hypothesis Testing I think.

Alright so I have no idea how to do this and I'd really love some help. Once I understand this one I'll be able to do the rest of my homework I think. Math is like a whole new language to me so I may have questions.

To test the hypothesis that a particular machine fills bags with 5 pounds of sugar, a quality control engineer randomly selects 9 bags and finds their weights to be
5.2 5.2 5.1 5.1 5.1 5.0 5.1 4.9 5.0

Assuming the bag weights are distributed normal, at the 2% level of significance, is the machine working properly? Be sure to state teh null and Alternative Hypothesis, as well as the test statistic and rejection region, or p-value you use to make your decision. Hint: use a two tail test.

2. $\displaystyle H_0:\mu=5$ vs $\displaystyle H_a:\mu\ne 5$

The test stat is a t with n-1=8 degrees of freedom

The value is $\displaystyle t^*={\bar X-5\over S/\sqrt{n}}$

The rejection region (also known as the critical region) is $\displaystyle (-\infty, -2.896)\cup (2.896,\infty)$

The p-value is $\displaystyle 2P(t_8>t^*)$ since the test stat seems to be positive.