# the normal probability distribution 1

# The Normal Probability Distribution

In Â§6.2 we are introduced to the Normal Probability Distribution and the special case of the Normal Probability Distribution, the Standard Normal Probability Distribution, which is a Normal Probability Distribution with mean (*u*) zero and variance (Ïƒ2) one.

**Watch these videos**

**https://www.youtube.com/watch?v=mFYvUxOO2T4**

**https://www.youtube.com/watch?v=uAxyI_XfqXk**

One way to find probabilities from a Standard Normal Distribution is to use probability tables.

- What exactly is a z score?
- What do we need to know to calculate a z score? (What variables?)
- What is the point of finding a z score? What are we doing?
- There is a z table in your book, or you can use an online one. A hint from Dr. Klotz: This is my favorite online z table. http://www.z-table.com/ Don’t lose that link!
- According to the table, what is the probability when z â‰¤ -3.00? Would that be a common occurrence or a rare occurrence?
- According to the table, what are the z scores for z â‰¤-2.15 and z â‰¤2.15? What about z â‰¤ -0.55 and z â‰¤ 0.55?
- Add each pair. Why do they total 1?