2008 3(d)

[m@tty]

I still don't get how you get the z value.. inverse normal on my calculator just gives area, mean and sd. Can't put in x either. What do I do?

The area is the probability, so here put 0.005 or 0.995. Since you are finding the Z value, you are working with the standard normal distribution, with SD of 1 and Mean of 0. Plug these values in and you'll find out the corresponding z-score.

[Munkea]

I will teach you guys another way to do this. I didn't look through the posts too well so forgive me if its already come up. But here goes:

I am not entirely sure if this can be done on the other forms of CAS. But I am using a CASIO Classpad 330.

Ok. First, go to interactive > distribution > normCDF. As obvious, put in the lower and upper no.s and the mean. In the 'standard deviation' box, put 'x' instead of a number. When you hit the 'ok' button, it will come up as a "wrong argument type". This is the fun part. Hit the 'ok' button and in the end of the normCDF part that you just typed, put in "=0.99". Then, go to interactive > equation/inequality > solve >ok. And Voila! You have the number sitting right in front of you. Using this, you don't have to do too much manipulation of formula or anything.

However, you might want to use this as a 'checking' mechanism because of the limited working out you can put. But, it is brilliant to know when your answer is correct  

This is how I approached the question. To show working out however, simply state


Yeah I don't really know how to show pi or sigma. Meh.

[98.40_for_sure]

\pi \sigma \mu for those symbols

[iGilly]

I still don't get how you get the z value.. inverse normal on my calculator just gives area, mean and sd. Can't put in x either. What do I do?

The area is the probability, so here put 0.005 or 0.995. Since you are finding the Z value, you are working with the standard normal distribution, with SD of 1 and Mean of 0. Plug these values in and you'll find out the corresponding z-score.

It took 3 pages, but I finally understand haha, thanks