reaching4thestars Posted February 27, 2011 Report Share Posted February 27, 2011 For a power function, when ur calculating your model .. do u have to use all 28 combination of the points? Or could you select a pair then get ur values? and if you do it the second way, how do you justify that that pair of points would give you something accurate??? Reply Link to post Share on other sites More sharing options...
dessskris Posted February 27, 2011 Report Share Posted February 27, 2011 For a power function, when ur calculating your model .. do u have to use all 28 combination of the points? Or could you select a pair then get ur values? and if you do it the second way, how do you justify that that pair of points would give you something accurate???just select a pair but don't just randomly select.. if you could use technology to show the power regression first, do it and see which two points that curve passes through the best. don't show it in your portfolio, though then you pick those points.I can't help with the justification but I guess you can research on power function to see if there is any characteristic or specialty of the power function (for instance, in quadratic they have a stationary points. in logarithmic they have asymptotes...) then you can relate it with these data points Reply Link to post Share on other sites More sharing options...
gba Posted February 27, 2011 Report Share Posted February 27, 2011 About how long is this portfolio supposed to be? I know the number of pages doesn't matter, but so far I only have 10 pages and I'm almost done, while everybody else I ask has like 15+ pages. I'm worried that either the quality/detail of my work isn't good enough, or I did something wrong/skipped some steps entirely. Reply Link to post Share on other sites More sharing options...
canadian.ib.girl Posted February 27, 2011 Report Share Posted February 27, 2011 For a power function, when ur calculating your model .. do u have to use all 28 combination of the points? Or could you select a pair then get ur values? and if you do it the second way, how do you justify that that pair of points would give you something accurate???What I'm doing is finding about 10 combinations and averaging the values I'm getting to calculate the model. Idk if that's what we're supposed to do :/ good luck Also, what does it mean by "implications of your model in terms of g-forces acting on a human being" ? Reply Link to post Share on other sites More sharing options...
BronxNerd Posted February 28, 2011 Report Share Posted February 28, 2011 Hey people! I am typing up my Math IA (the one about G-force Tolerance) and I was wondering what I have to do when they ask me to: "to define the appropriate variables and parameters, and to identify the constraints for the data." ? Any ideas? Reply Link to post Share on other sites More sharing options...
reaching4thestars Posted February 28, 2011 Report Share Posted February 28, 2011 (edited) Hey people! I am typing up my Math IA (the one about G-force Tolerance) and I was wondering what I have to do when they ask me to: "to define the appropriate variables and parameters, and to identify the constraints for the data." ? Any ideas?variables - defining what you are going to let your variables be i.e. let x be timeparameters- transformations of the functionconstraints - limitations of the data givenhope it helps when is yours due?? Edited February 28, 2011 by Desy ♫ no text speak! 2 Reply Link to post Share on other sites More sharing options...
BronxNerd Posted February 28, 2011 Report Share Posted February 28, 2011 Thanks!! That helped a bunch. Mine is due this week. I think by Friday. I am not sure lol. I think she, my math teacher, said we are going to work on it during class. She is going to teach us how to copy the screen of the Graphing Calculator onto a Word Document. Reply Link to post Share on other sites More sharing options...
dessskris Posted February 28, 2011 Report Share Posted February 28, 2011 Also, what does it mean by "implications of your model in terms of g-forces acting on a human being" ?I think it means you need to relate your mathematical conclusion with G-force. For example, you look at the graph -- how G-force relates with the toleration time -- and then you describe it in terms of G-force. Maybe you can conclude that if G-force is greater, human beings can tolerate it for a shorter time. Something along those lines Reply Link to post Share on other sites More sharing options...
Deeyor Posted February 28, 2011 Report Share Posted February 28, 2011 (edited) Hey desy!I love your advice and recently needed a lot for my math portfolio!Im doing the G-force tolerance one and needed a few anwsers!So I began with finding a model function and used the logarithm one (i really have no evidence how, just saw ur comment on a forum to use it so i did ?) using the equation you provided y=a+b*ln(x) where a =11 and b = -1.82 (are these right?) i used point 1,11 and 3,9 to solveWhat should i do after? How can i use technology to find the power function? please guide me !ThanksHey rabyl thank you! Sorry I am taking too long to respond ok you got the equation right already.. anyhow I don't have access to any graphing software currently so I can't check if it fits the data well. but after you get that equation, plot it on the same axes with the original data series. Then comment on how well it fits After that, umm what GDC do you have? If you have a TI, just use it to plot the data and find the best fit power regression if you don't know how, I wrote an instruction here Any doubt or more questions just ask!How exactly would one go about finding both "a" and "b" in the the logarithmic function? I tried to work out the solution however I think I am wrong. Edited February 28, 2011 by Deeyor Reply Link to post Share on other sites More sharing options...
dessskris Posted February 28, 2011 Report Share Posted February 28, 2011 How exactly would one go about finding both "a" and "b" in the the logarithmic function? I tried to work out the solution however I think I am wrong. Pick 2 sets of values of t and G, and substitute them into the general equation then solve them simultaneously.Here is an example:Those are random values of x and y, though not the ones in this task Reply Link to post Share on other sites More sharing options...
Deeyor Posted February 28, 2011 Report Share Posted February 28, 2011 How exactly would one go about finding both "a" and "b" in the the logarithmic function? I tried to work out the solution however I think I am wrong. Pick 2 sets of values of t and G, and substitute them into the general equation then solve them simultaneously.Here is an example:Those are random values of x and y, though not the ones in this task Thanks a ton! Yet are you not subtracting 7 from 13? If so would you not get 6 rather than 5? Sorry, the 5 is confusing me 1 Reply Link to post Share on other sites More sharing options...
dessskris Posted February 28, 2011 Report Share Posted February 28, 2011 Thanks a ton! Yet are you not subtracting 7 from 13? If so would you not get 6 rather than 5? Sorry, the 5 is confusing me ohhh haha yes, it should have been 6! lol I substracted incorrectly thank you for pointing out my mistake Reply Link to post Share on other sites More sharing options...
Tommy.D Posted March 2, 2011 Report Share Posted March 2, 2011 Thanks a ton! Yet are you not subtracting 7 from 13? If so would you not get 6 rather than 5? Sorry, the 5 is confusing me ohhh haha yes, it should have been 6! lol I substracted incorrectly thank you for pointing out my mistake Hey Desy, I have a few questions about this IA, actually a lot:) so im wondering if you have any IMs so i can ask you? thanks! Reply Link to post Share on other sites More sharing options...
dessskris Posted March 2, 2011 Report Share Posted March 2, 2011 Hey Desy, I have a few questions about this IA, actually a lot:) so im wondering if you have any IMs so i can ask you? thanks!Hello Tommy.D,I am sorry to say this but would you just post questions in this thread instead of discussing it with me one-to-one? because my posts need 'moderation' from our Moderating Team as I cannot give out answers. and if you get the 'hint', everybody should also get the same 'hint', thus we should just discuss this in the IA thread. I apologise to you Desy Reply Link to post Share on other sites More sharing options...
Tommy.D Posted March 2, 2011 Report Share Posted March 2, 2011 Hey Desy, I have a few questions about this IA, actually a lot:) so im wondering if you have any IMs so i can ask you? thanks!Hello Tommy.D,I am sorry to say this but would you just post questions in this thread instead of discussing it with me one-to-one? because my posts need 'moderation' from our Moderating Team as I cannot give out answers. and if you get the 'hint', everybody should also get the same 'hint', thus we should just discuss this in the IA thread. I apologise to you DesyNo, its all good. So for the first part it says to define variables and parameters and any constrint. what specifically do i have to say? Also, ater plotting the data in excel, i found out the its actually a power function, and it asks to find an equation(or a model) to fit the data, do i have to create a power fucntion by hand or do i just use the one generated from excel? Thanks. Reply Link to post Share on other sites More sharing options...
dessskris Posted March 3, 2011 Report Share Posted March 3, 2011 No, its all good. So for the first part it says to define variables and parameters and any constrint. what specifically do i have to say? Also, ater plotting the data in excel, i found out the its actually a power function, and it asks to find an equation(or a model) to fit the data, do i have to create a power fucntion by hand or do i just use the one generated from excel? Thanks.Sorry I guess I'm taking too long to write a reply!Umm I am not that sure about parameters actually but for that part you should mention what P and t represent (population and time) and roughly their domains if possible. After that once you start modelling you can introduce the parameters there. That is what I would do. However I am not so sure either sorry!Do not use excel for that part. Model one algebraically Start with the general equation y=axb then substitute in 2 sets of values of x and y and solve for a and b simultaneously Reply Link to post Share on other sites More sharing options...
Tommy.D Posted March 4, 2011 Report Share Posted March 4, 2011 Is power function the right answer? since I saw there were a lot of people used Log function as their final answer. And i should have 2 equations by the time i finish the project right? One for horizontal g-force, and one for vertical? Also, when it asks to "Discuss the implications of your model in terms of G-forces acting on a human being" .. I really dont know what i should talk about. Reply Link to post Share on other sites More sharing options...
dessskris Posted March 5, 2011 Report Share Posted March 5, 2011 Is power function the right answer? since I saw there were a lot of people used Log function as their final answer. And i should have 2 equations by the time i finish the project right? One for horizontal g-force, and one for vertical? Also, when it asks to "Discuss the implications of your model in terms of G-forces acting on a human being" .. I really dont know what i should talk about.Yes it is. Logarithm fits the shape but not as well as a power function does it's better to model a power function than a logarithm function I suppose.Umm 3 actually:One for Gx, analytically modelledAnother one for Gx, modelled using technologyOne for Gz, modification of either the first or the second functionThat part, describe the graph in terms of G-force. Like maybe if the force is greater, human beings can tolerate it for a shorter period of time. Or maybe if the force exceeds this amount, human beings cannot tolerate it (asymptote). Something along those lines Reply Link to post Share on other sites More sharing options...
FurubaRei Posted March 5, 2011 Report Share Posted March 5, 2011 How did you guys get to the equation...?I just plotted it into Excel and grabbed the exponential function.Can someone explain to me why it isn't Power but it is Exponential?Power seems to fit even better too.And how would you derive that equation by hand...I also noticed someone talking about R-squared value... what is that?That is something that I am very confused with as well.What is the difference between a Power function and an Exponential function?The R squared value is the accuracy of the equation. If it's .95 and above its a good accuracy value when I put the R-squared in i got .99But i used a power function... is that not what it is?? Reply Link to post Share on other sites More sharing options...
dessskris Posted March 5, 2011 Report Share Posted March 5, 2011 But i used a power function... is that not what it is??Yeah it is.. What do you mean? Why are people afraid of modelling a power function? my GDC tells me that a power regression fits better than exponential and logarithmic. So don't worry, you are on the right track! Reply Link to post Share on other sites More sharing options...
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