Logarithmic calculation??? I think...

[merwinmay]

So it has been a while since my math days and now I am trying to figure out the equation for this problem. I think it is a logarithmic calculation but can not seem to find what I am looking for on google. I have these points that form a line (obviously not a straight line)
X Y
0 0
530 1567
1632 3360
3280 4447
3804 4687

Then I need to find the answer for Y where X=203. So it should be somewhere around 595. Can anyone tell me how to solve for Y? Thank you.

 

[Dr.Peterson]

It can't be just a log, because 0 would not be in the domain.

We also can't ever claim to know "the" formula just from a few values. There are very many possible formulas.

I presume you are guessing a logarithm based on your impression of the shape of the graph. Do you have any other information from which one could determine the actual form of the equation? If we knew where the numbers came from, we might be able to make a better guess, at least.

 

[merwinmay]

So the X is the time temperature factor or TTF and the Y is PSI or strength. Basically I have a lab file of certain concrete breaks over time. These are all done in the lab then when concrete is actually placed we can calculate the TTF but I need to find the strength (PSI) based on the TTF. Hope that helps.

 

[Deleted member 4993]

So it has been a while since my math days and now I am trying to figure out the equation for this problem. I think it is a logarithmic calculation but can not seem to find what I am looking for on google. I have these points that form a line (obviously not a straight line)
X Y
0 0
530 1567
1632 3360
3280 4447
3804 4687

Then I need to find the answer for Y where X=203. So it should be somewhere around 595. Can anyone tell me how to solve for Y? Thank you.

Are you allowed to use MS_Excel?

 

[merwinmay]

I can use Excel on this PC but I need to be able to replicate it outside of Excel on a web form.

 

[Dr.Peterson]

So the X is the time temperature factor or TTF and the Y is PSI or strength. Basically I have a lab file of certain concrete breaks over time. These are all done in the lab then when concrete is actually placed we can calculate the TTF but I need to find the strength (PSI) based on the TTF. Hope that helps.

I used this information to search for information on the relation you are studying, and have found one reference that suggests the relationship should have the form Y = C e^(k/X^n). That's more than I can do on Excel.

I haven't done enough searching to find anyone who actually talks about fitting the data to a particular form. (Some just say to draw the best-fit curve, without saying how.) Maybe we need to see your sources.