Hello everyone its valley but you also all know me as Michelle. Here's the scribe post for today. In today's class we talked more about z-scores and we learned a couple of new functions on our calculators. Besides using shadeNorm there is another way to figure out the percents of z-scores and that is the commulitive distribution function. Here's an example.

Find the percent of z-scores in a normal standard distribution that are:

a) below z = 0.52

Now to figure this out normally you would press 2nd [vars] and then you would go to the DRAW menu. ShadeNorm is the first function in the menu. After pressing ShadeNorm in the bracets you would enter -5, 0.52. Remember the smallest number is to be entered first. And the reason why you enter -5 is because the curve continues on past the -4 mark for the normal bell shaped curve. So when finished your answer should look like so.

ShadeNorm( -5, 0.52) = 0.6985

Now the new function that we learned today is the commulitive distribution function.

To find this on your calculator you would press 2nd [vars] and its the 2nd function in the menu. It looks like so...normalcdf.

The C stands for commulitive which means you add up the numbers as you go along.

For example if you have a group of 4 then another group of 4 and then a last group of 3 you would add them up as so...4...8...11.

The 2nd function that we learned was the probability distribution function. To find this on your calculator you would press 2nd [vars] and it is the first function in the menu.

The P stands for probability which in this case tells a value at a point.

As I was saying earlier that when using the ShadeNorm or the Normalcdf function you will see that you obtain the same answer.

ex. Find the percent of z-scores in a normal standard distribution that are:

a) below z = 0.52

ShadeNorm( -5, 0.52) = 0.6985

Normalcdf( -5, 0.52) = 0.6985

As you can see your answers are the exact same.

Besides dealing with z-scores again and learning a couple of new functions on the calculator we went over the homework questions from last night. I would try to help and explain them myself but even I am having some difficulties with the problems so I apologize for that. I am gonna get some extra help with that so that the next time I do a scribe I can help everyone out 100%. I hope what i have written has helped you all out. The next scribe is......David-san!

## Tuesday, March 25, 2008

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