Develop a model in the form of y=y0e^kt
- Thread starter rsyed5
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D
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You need to calculate 3 constants - and you are given 7 data-points.
Are you supposed to ind find a "best-fit" line using statistical methods?
Are you allowed to use software like MS-excel?
Please share your work with us so that we know where to begin.
Hi sorry in the last post i accidentally added another paragraph which might have confused you
So basically we are suppose to make an equation from this data in the form of m=m0e^kl to state a relationship between the mass, m, and the length, l, of the fish.
In other words find a model that best fits the data given. (this is in an exponential equation form). I will paste the whole page here if you want, just ask me.
D
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Are you allowed to use commonly available software (e.g. Microsoft Excel) to accomplish this task?
Hi,
Yes we can use any software, I started with using excel as well, put the data in, then I used a trend line (exponential) on the chart and displayed the equation. But the trend line equation is not the actual equation, it is very close. I think that the question doesn't want us to graph it though because it does not say, I'm suppose to find the initial value m0 and k using algebra and calculus techniques but normally the initial value is given so its easy to go on instead in this one I think we just use one or two points given in the data table to figure them out. But that's where I get stuck.
P.S ( The trend line equation I got using excel was y=25.713e^0.0873x )
D
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I know that because the trendline i tried was exponential, and it did not fit the data points plotted exactly and we are suppose to find the line of best fit. I checked with my teacher though and she said we don't only have to use exponential with regards to the trendline we can try all the others so I tried polynomial order 4 and that fitted the points best from all the other options, here's what I got:
The problem now is that how do make the equation (y= -8e-05x^4+0.0245x^3-0.3307x^2+2.1851x+38.151) into the form of an exponential equation(m=m0e^kl) as asked in the question?
HallsofIvy
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I am puzzled by your question. You say that, after not being able to find an exponential, you checked with your teacher, "and she said we don't only have to use exponential with regards to the trendline we can try all the others".
Now you are trying to force it to be an exponential? You can't do that. A polynomial is not an exponential. And any exponential you try that is close to the polynomial you got for the trend line can't be any better than those you got directly from the trend line.
Now you are trying to force it to be an exponential? You can't do that. A polynomial is not an exponential. And any exponential you try that is close to the polynomial you got for the trend line can't be any better than those you got directly from the trend line.
You are right, you can't force it to be exponential, the teacher was actually talking about another method (also using excel) about the same question so I got confused between the two. The exponential trend line is the answer.
Hi rsyed:
Maybe you mispoke, but I would like to ensure that you understand the meaning of best-fit.
A best-fit line (in this case, a curve) will not match all data points exactly. It's a model that can be used to approximate a trend, in a way that reduces error with respect to known data as much as possible, for the particular class of function chosen (eg: exponential, logarithmic, polynomial).
Cheers
