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Monday, April 10, 2006 


Hey whats up everyone. Im the scribe for today so I'll go over what happend in class today.

First thing at the begining of class Mr. K handed back a bunch of old work for past units. All I can say from looking at my marks then is I miss the marks i got in the Marticies unit. Anyways I think after that Mr. K anwsered some questions people had on blogging on blogging. I'm not sure what the origional question was but it involved finding the area of part of a curve multiple ways.

The first example he gave was find area of everything under the Z score of -2. One way to do it is: by using shadnorm function of your calculator. With using shadenorm with Z scores the first digit you plug into your calculator is the low value, which in this case is -5. ( this is because, I'm not quite sure of this number but 99.99% of data is between 5 standard deviations, so using -5 is more than enough to get everything on the low end) Then you hit , then plug in the high value, in this case it would be -2. This is what You should get. (note: shadenorm draws a graph)

shadenorn( -5,-2)= o.o25

Another way to do the same question is by using the normalcdf function of ur calculator. The only difference between shadenorm and normalcdf is shadenorm draws a grapgh.


Another way to do the same type of question is with using the real/normal values not the Z-scores. Basically the only difference between this and the question above is when using the normal values you need to plug the mean and standard dev. into your calculator along with the low and high values. The Mean for the example was 62 and the standar dev. was 6. We were supsota find the % of data up to the Z score of -2. Well one way of finding what the normal value of a Z-score of -2 is with the mean of 62 would be to plug it into that formula:
z=x-x(mean)/standard dev. But and easier way to do it would be to just to subtract the amount of Z scores you want to find from the mean. Kinda hard to explain. The low value we want to find sould be equal to -5 Z-scores like in the first example. And one Standard dev. = 1 Z-Score would to find -5 Z-score would would take the mean and subtract it from 5 standard dev.

62-(5 x 6) = 32 < this is our low value

So to find the high score you basically do the same thing but you only subtract 2 Z-scores for the mean

62-(2 x 6)= 50
Then all you have to do is plug the information you have into your calculator. You can either use shadenorm or normalcdf. Either way you should get the same thing

shadenorm(32,50,62,6)= .025
normalcdf (32,50,62,6)= .025
(remember you have to plug in the mean and standard dev. to let the calculator now that your not using Z-scores)

And then after this we were given our statistics pre-test. After that we got into groups to discuss our anwsers and then like usual only one person had to hand one paper with the group members names on it. Well thats about it for what we did in class today. The last thing I got to say is remember to do your blogging on blogging before your test. I'm gonna do mine now while I'm logged into blogger.


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