Critical Values > Area Under a Normal Distribution Curve

## How To Find the Area Under a Normal Distribution Curve

How you find the area under a normal distribution curve depends on what your shaded area looks like. Before you can solve for the area under a normal distribution curve, you must be able to imagine what you area looks like. The best (albeit optional) way to imagine this is to make a sketch. For example, let’s say you were give a z-score and were asked to find the area between that score and z=0 (the mean). Your sketch might look like this:

There are seven ways your sketch could look, depending on what values you were given. **Once you have drawn your sketch, look at the pictures below**. Click on the image that looks like your sketch. the link will take you to a step-by-step guide on how to find the area under a normal distribution curve for that shape. Many of these also have short videos showing the steps.

## Choose One

**Tip:** Drawing sketches in probability and statistics isn’t just limited to normal distribution curves. If you get used to making a sketch, you’ll also have an easier time with creating complicated graphs (like contingency tables).

Check out our YouTube channel for hundreds of statistics help videos!

I like this a lot. Too bad there isn’t always a picture to click on.

Hi Mary,

Do you mean that the picture is missing in your browser? If so, can you let me know what browser you are using?

Or do you mean that you’ve come across a problem type not addressed here? If so, let me know and I’ll see what I can do :)

Stephanie

Yeah when you come across questions like these they are easy with the pictures. I can understand it better, for the most part. I just have to learn how to read the question fully before I jump on it. I get myself all worked up and then I can’t do the problem.

I absolutely agree with Lisa. I get very overwhelmed when I look at the word problem as a whole. But, I’m starting to learn how to look at the numbers and figure out where to put them in the equations. Finally, it feels like it’s starting to click

I bought your book but I’m not sure where to look for the following step-by-step problem solver. I’m on chapter 8 sections 8.1 & 8.2(Statistics Informed Decisions Using Data, M. Sullivan, III). I can solve part a) to the questions but then get lost (my answers aren’t matching the text answers). Here is an example: 8.2 #17 b)What is the probability that in a random sample of 500 adult Americans less than 38% believe that marriage is obsolete? (Note: 39% is the ‘mean’ or P; p-hat?) The text answer is P(‘p hat’ < 0.38)=0.3228 [Tech: 0.3233]* (*I'm allowed to use my TI-84plus calculator too).

where do I look in my 'Practically Cheating Handbook'? Please guide me. I'm hoping you can help (soon). Thanks!

It looks like this problem is using the z-table or t-table. Does the question give you the standard deviation?

Hi..

how to find the area of p (0<z<0.855)

I can be able to find 0.85 only. How to find for 0.005. Pls help me

It would be in between 0.85 and 0.86.