Σ with Casio Graph 35+ list

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cricrivlm -  
quent217 Posted messages 424 Status Membre -
Hello,
I have a Casio Graph 35+
I'm having a problem with using the summation symbol Σ in run maths while using the lists entered in stat.
Let me explain:

Taking the example of the standard deviation with 6 values and a mean of 12 (I know you can get it directly in stat, but this is just to explain my issue):

When I use the symbol Σ in run maths, I need to fill several boxes []:
- below: [] = [] (on paper, this gives --> i=1)
- above: [] ( --> 6)
- and to the right: ( [ ] ) ( --> ni(xi-12)²)

So I tried the following:
- below: [] = 1
- above: 6
- to the right: list2(list1-12)²

I'm missing one box to fill, I've tried lots of things but nothing works.
I don't even know if the rest is correct.

Sorry if my problem isn't clear, I don't see how to explain it otherwise.
Does anyone know how to do this?

Thanks in advance.

1 réponse

quent217 Posted messages 424 Status Membre 348
 
Hello,
The missing location corresponds to the variable that will vary, and you will need to use this variable in the formula on the right. In fact, you have to write it exactly as on the paper. That is to say:
- below: I=1
- above: 6
- on the right: list2[I](list1[I]-12)²

But if I remember correctly, this formula calculates the variance; if you want the standard deviation, you need to calculate the square root of the result.
5
cricrivlm
 
I'm going to try it like that, thanks
But I found the Sum function that works well with the lists
Ps: yes yes I know for the standard deviation you have to divide by the sample size and take the square root it was just for the example
Thanks anyway
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quent217 Posted messages 424 Status Membre 348
 
Yes, indeed there is also the Sum function, but in some cases you have no choice but to use the sigma, that's why I didn't mention it.
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