Calculating Probability Using Z-Score & Normal Distribution

Calculating Z-Score

This video covers how to calculate z-score in a few different situations. Sometimes you're given a whole list of numbers, while other times you get a word problem that tells you the mean and standard deviation and asks you to find the z-score of a particular data point.

How To Spot Z-Score Table Problems

Before you can do a z-score table problem, you've got to know what they look like. So this video gives you everything you'll need to know to spot these puppies on the test, from the easy ones to the most crazy one I've ever seen.

How To Read A Z-Score Table

This video shows you how to use those z-score tables which give you the "area to the left" of a z-value. They can be a bit confusing when you first see them, plus there's some wacky stuff going on around zero.

How To Use Z-Score Table To Calculate Probability & Proportion

Now that we've covered the basics of this type of problem in the preceding videos, we're finally ready for 30 minutes of awesome examples which will make you the master of transforming x's to z's and back again!

Z-Scores In Reverse-Calculating Cutoffs From A Probability

Once you already know how to do the crazy z-score table problems in the previous video, this video covers a particularly over-the-top version of those problems: instead of giving you a cutoff x and asking you for the percentage above or below that value, they give you a percentile and ask for the cutoff x value. Pretty crazy.

Z-Score Table Calculations On Your Calculator

This video covers how to use your calculator to replace the z-score table that's in your book. If you don't get to use a calculator on the test, that's obviously not going to help you, but many z-table problems can be done just on your TI-84.