HP Prime - Statistics
08-22-2014, 01:19 PM
Post: #4
 paul.hermans@benemtech.com Junior Member Posts: 9 Joined: Aug 2014
RE: HP Prime - Statistics
To clarify for Walter whose answer was about as useless as any i have ever seen as it did not answer the question. I will rephrase the question to better explain what i need help with.

Background:
I have a new calculator that I am trying to learn to use. It is an HP Prime. The manual sucks and makes it hard to find anything of use, and on calculator documentation is a joke. In the manual, if i don't already know the name of a function, good luck finding it.

Current Situation:
I have to use this calculator on a test of which statistics is a very small portion of the material covered. The test has limited time, and I am trying to figure out how to use the Prime to answer certain questions QUICKLY.

I forgot to mention that I was referring to a Normal Distribution but my understanding was that Z-Scores are also sometimes referred to as standard scores and are always part of a normal distribution (not sure this is correct, but that is why i didn't spell out that it was a normal distribution)

So, how do i calculate the area under the curve (yes, the normal distribution curve) between two values of Z. Yes, if i had a definition of the function f(x) = ?? then I could try to integrate, but my memory tells me that was a very time consuming and difficult option and leads to nothing useful for this task. Yes, I could look up values in a table, but no table will be provided. Yes, I could memorize certain values like .683 being between +- std. deviation and estimate, but that is pointless. So what am i left with? Oh, using the calculator to calculate it.....silly me, why didn't I think of that?

There is a function in the HPPrime called normald_cdf(mean, std dev, value) which calculates the area under the curve to the left of the value specified. So, back to my original question, is there a faster/better way to calculate the area between two values for this distribution?

I could do normald_cdf(mean, std dev, upper_value) - normald_cdf(mean, std dev, lower_value)
but that takes forever to enter, so without asking for more condescending, useless answers, is there a way to use the HP Prime to do this faster?

For reference, on the TI calculators a function exists that takes an additional argument so i can specify the upper and lower bound of the region i want to calculate the area for, i am looking for something like this in the Prime.