HP Forum Archive 13

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HP 48gx scatterplot? Message #1 Posted by Karen Gibson on 16 May 2003, 10:54 a.m. Any help with this question is greatly appreciated. I apologize now for my lack of knowledge on this calc. I've only had it a month, I've figured most of the things out on my own, but this one has me stumped. I am doing a scatterplot, that part I have down. I need to get the equation for the data after I have plotted it. I've tried using the STATL button on the menu, then FCN VIEW to get the equation. For some reason it is returning an incorrect equation. I know this because I've tried several out of my Algebra book and do not get the correct answer. When I do the STATL instead of following the data plotted it does a diagonal line accross the screen and this is the equation it returns. Can anyone help? Thank you, Karen

Re: HP 48gx scatterplot? Message #2 Posted by R Lion on 16 May 2003, 11:26 a.m., in response to message #1 by Karen Gibson Hi Karen: Could you mail me with the data and the answers (the correct and the incorrect ones) More help about hp48 in http://groups.google.com/groups?as_ugroup=comp.sys.hp48 Raul

Re: HP 48gx scatterplot? Message #3 Posted by Karen Gibson on 17 May 2003, 11:09 a.m., in response to message #2 by R Lion Hi Raul, Here is the info: x values: 0, 7, 14, 20, 24 y values: 26.2, 19.2, 16.6, 18.8, 19.5 Plot is stretched u shape opening upward. Correct answer is: f(x) = .0402302792x^2 - 1.214631021x + 26.02596908 Answer on my HP: 23.2788829787 -.247606382979x Thanks for the help. Karen

Re: HP 48gx scatterplot? Message #4 Posted by R Lion on 17 May 2003, 12:16 p.m., in response to message #3 by Karen Gibson You are getting the Linear regression but you want a polynomial regression. You need some extra software (i.e.: http://www.hpcalc.org/hp48/math/statistic/bfit.zip ) I have got your expected results with that. Hope this helps. Raul

Re: HP 48gx scatterplot? Message #5 Posted by Karen Gibson on 17 May 2003, 2:05 p.m., in response to message #4 by R Lion Thanks Raul, I'll try that, need to get some more hardware first.

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