Expected Value on TI-nspire

[DBeth]

My AP Stats students are finding the expected value (mean) of a
probability distribution today. I knew how to do it easily on the
TI-83/84 calcs: enter X in L1, P(X) in L2, and then go 1-Var Stats
L1, L2 and BAM!!

For instance, I did the table as an example in class where X = 0, 1,
2, 3, 4 with probabilities of 0.1, 0.2, 0.2, 0.4, and 0.1
respectively. E(X) = 2.2 and Var(X) = 1.166.

On the TI-nspire, I went to the same area, Menu:Statistics:1-Var
Statistics and selected 2 lists. I entered the names of the lists it
asked for, but then I get separate mu values...not one expected
value. I got 2.000 and 0.200 which I know add to 2.2, but it seems
putzy to me.

What's the correct/easier way?

[Andy Kemp]

Hi there,

Your mistake is in selecting 'two lists'.  You don't have two lists you have one list with frequencies...

Select 1 List, then your X1 List is your X values, and the probabilities are your Frequency List.

This will then give you x-bar which is E(X) and sigma-x which is sqrt(Var(X)).

Pretty much the same steps as on the 84...

Cheers

Andy

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[DBeth]

perfect! Thanks for the help. Knew it would be something simple like
that.

On Nov 29, 12:40 pm, Andy Kemp <a...@1kemp.co.uk> wrote:
> Hi there,
> Your mistake is in selecting 'two lists'.  You don't have two lists you have
> one list with frequencies...
>
> Select 1 List, then your X1 List is your X values, and the probabilities are
> your Frequency List.
> This will then give you x-bar which is E(X) and sigma-x which is
> sqrt(Var(X)).
>
> Pretty much the same steps as on the 84...
>
> Cheers
> Andy
>

> On Mon, Nov 29, 2010 at 5:52 PM, DBeth <damionb...@gmail.com> wrote:
> > My AP Stats students are finding the expected value (mean) of a
> > probability distribution today.  I knew how to do it easily on the
> > TI-83/84 calcs:  enter X in L1, P(X) in L2, and then go 1-Var Stats
> > L1, L2 and BAM!!
>
> > For instance, I did the table as an example in class where X = 0, 1,
> > 2, 3, 4 with probabilities of 0.1, 0.2, 0.2, 0.4, and 0.1
> > respectively.  E(X) = 2.2 and Var(X) = 1.166.
>
> > On the TI-nspire, I went to the same area, Menu:Statistics:1-Var
> > Statistics and selected 2 lists.  I entered the names of the lists it
> > asked for, but then I get separate mu values...not one expected
> > value.  I got 2.000 and 0.200 which I know add to 2.2, but it seems
> > putzy to me.
>
> > What's the correct/easier way?
>
> > --
> > To post to this group, send email to tins...@googlegroups.com

> > To unsubscribe send email to tinspire+u...@googlegroups.com<tinspire%2Bunsu...@googlegroups.com>