# IA Body Mass Index

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Ok...so this project isn't too bad. The only thing many classmates and I are stuck on is where we have to find the BMI data from another country. Anybody have any success with this? Any help would be really appreciated.

*The other two thread for the BMI project were merged with this one*

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I only completed my Maths BMI Portfolio this week The first time I read over the questions I assumed that the research question would be the easiest, but lo and behold since when was anything related to IB easy? They even managed to make research difficult!

I was able to find some data on school girls in Australia, but for a very limited age range. Unfortunantly by the time I actually found data that would be good enough, the deadline passed and our Maths Portfolios were submitted and locked up in a dark drawer I still can't believe that I missed it

Edited by syrianstar
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I found data for Guatemalan kids: http://www.unu.edu/unupress/food2/uid02e/uid02e0e.htm

Better than nothing - we also had to hand in completed portofolios two weeks ago ...

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heyy everyone !!! I need help with my BMI portfolio !!! I've a couple of questions about some of the steps in it

plz ! if someone has already done it.. give me your e-mail adress to chat a lil' bit !!

thank you all =)

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ive heard people say the american female bmi data is quadratic..natural logarithm..quartic..AHHH! Does anybody know for sure or have any idea?

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It's polynomial of 3rd degree or higher. Should you choose this option, I've posted the instructions on how to obtain polynomial of any degree (up to maximum number of points in your set of data, to be precise) here. You will find data for median BMI of females here. Another option is to mess around with the sine or cosine function. I can also assist you with this one if you like, but I'd go for polynomials if I were you.

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Hello all

I seem to be having the worst time trying to find an age-vs-BMI index for women in countries that are NOT a part of the commonwealth.

All that I have googled thus far has lead me, in some way or another, to the same World Health Organization site. Which is driving me CRAZY!

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The third question states:

Use technology to find another function that models the data.

I am absolutely baffled by this question because the previous one before it pretty much states the exact same thing.

Is the question asking for another equation or a whole different type of function because the only type of function that I can find that fits is a polynomial.

Does it have something to do with the order?

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It's asking for another equation; that is, use technology to find a function like the one you propose (a polynomial in this case) but that fits the information better.

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Yeah exactly what Robertomx said. You could either use Graphmatica's function (its a free software you can download), or use a sine regression.

And #2 differs from #3 because #2 asks you to derive the function manually whereas #3 is asking for the technological function, you dont have to show your calculations etc in this part.

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It asks you to find the common differences between the graphs as well..

i dont get that question lol!

also is the quadratic equation sufficient enough to find the BMI at age 30...cuz that the only graph that goes up like that....except for the linear function...

im confused T_T....cuz i dont get technology even got those numbers ....i gotta hand it in tomorrow hehe

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im really stuck with the whole internal assesment haha

can someone maybe help me ?

i still dont get wat a parameter is and i dont get which functions to use and i dont get how to mention common differences in the graphs lolll.

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It asks you to find the common differences between the graphs as well..

i dont get that question lol!

also is the quadratic equation sufficient enough to find the BMI at age 30...cuz that the only graph that goes up like that....except for the linear function...

im confused T_T....cuz i dont get technology even got those numbers ....i gotta hand it in tomorrow hehe

Hey,

If you go to Vernier.com and download "Graphical Analysis 3.4 demo" it helps sooo much for this portfolio!! It does the whole technology thing all by its self, like it finds the function that models it and everything.. this thing saved my mathematical life

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Hello all

I seem to be having the worst time trying to find an age-vs-BMI index for women in countries that are NOT a part of the commonwealth.

All that I have googled thus far has lead me, in some way or another, to the same World Health Organization site. Which is driving me CRAZY!

www.halls.md/bmi/lasting.htm (UK women)

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Ha, so I am pretty sure I know you Chantel.

Anyways. So I understand this portfolio pretty well, but I am soooo confused on how to find the BMI of the 30 year old. All my graphs go down, and the one that goes up again does it after ... If that makes sense.

I used the technology equation for a polynomial to the 5th power which was the only one that did not slope way down off the graph to find the 30 year old. Is this one right? I drops down to about 20 which does not really make sense on what the actual BMI of a 30 year old should be. (On all the websites I went to they said about 26, or 25ish.) So yeah ... anyone care to help me on this?

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who's doing this math portfolio,

i am??

anyone having difficulties??

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Okay so we are working on BMI data. We have to find a function that fits the data and models the behavior of the graph. It looks like it could be a cubic function, but which one should I use? y=ax^3+bx^2+cx+d or y= a (x+1)(x)(x+5)+d ??? The first one is the most basic form, but is also harder to explain when you are doing translations and whatnot. The second one is much easier to explain, but what is that equation called? Also what is it in it's "variable form", with all the a, b, c, etc.? Another problem with the second one, is how do I show that I got there? It's not the most obvious equation.

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Well, I used the first one. I picked 4 values and thus I had 4 variables and 4 equations. I solved them and I got my new equation. Where is your problem explaining the step?

Well, I've got another question. The portfolio asks in the end

"Use the Internet to find BMI data for females from another country. Does your model fit this data? If not, what changes would you need to make? Discuss any limitations to your model."

Does anyone know where I can find BMI data? I couldn't find any so far.....

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