Finding variance using HP

[Dreary]

How do you find the vriance for weighted data using the HP calculator?
Amount, Frequency
$1.50, 4
$2.00, 7
$3.25, 5
$1.33, 3
I usually get the mean by:
$1.50, ENTER, 4, SIGMA+
$2.00, ENTER, 7, SIGMA+
$3.25, ENTER, 5, SIGMA+
$1.33, ENTER, 3, SIGMA+
Then: g Xbar w
But how do you then find the variance? Thanks.

 

[mwvt9]

I don’t have my calculator in front of me, but you have to hit g then there is a button near the Xbar that is s. It stand for standard deviation. After you have that just square it.
I am sure you already know this, but it will calc SD for a sample not a population unless you make an adjustment.

 

[Dreary]

Thnaks but this doesn’t work for weighted data.

 

[mwvt9]

Oh, I see what you are saying. I will take a look at the manual if I get some time.

 

[mwvt9]

HP 12c manual
http://www.hp.com/ctg/Manual/bpia5184.pdf
Page 99 says that you should check out the solutions manual.
HP Solutions manual:
http://h10032.www1.hp.com/ctg/Manual/c00367123.pdf
p. 106 may have what you are looking for…….
Seems like alot of work though.

 

[Dreary]

Thanks for the pointer… Yes, it is on page 106, but there is no way I’m gonna make 10 (I counted them) key strokes after entering the data in order to get the variance! uh.
I guess for teh exam, I just get the mean, and then do the variance by hand.

 

[mcf]

Any similar guidance for the BAII+?