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# Modelling curves Watch

1. Hi everyone. I have my C2 exam tomorrow and I am very worried about one thing which involved modelling curves. When doing past papers I get the marks for drawing the graphs involving calculations of logarithms required for plotting them. However when I do the calculations to find out the constants involved especially the gradient , I do not get the answer in the range of what the mark scheme says. I am doing it as accurate as possible , even with the calculator I was keeping the values as they were but still it's not in the range. I am calculating the gradient as :change in y divided by change in x. Could anyone help me with this problem?

Thank you
2. (Original post by beatrice15)
Hi everyone. I have my C2 exam tomorrow and I am very worried about one thing which involved modelling curves. When doing past papers I get the marks for drawing the graphs involving calculations of logarithms required for plotting them. However when I do the calculations to find out the constants involved especially the gradient , I do not get the answer in the range of what the mark scheme says. I am doing it as accurate as possible , even with the calculator I was keeping the values as they were but still it's not in the range. I am calculating the gradient as :change in y divided by change in x. Could anyone help me with this problem?

Thank you
I think you need to give us a bit more info to go on

Can you post an example question showing what calculations you've tried to do, and how/where it disagrees with the answer?
3. I've attached jan 2013 c2. As k I got 0.013. It is the last question on this paper. I did change in y divided by change in x.

Thank you for your help

(Original post by davros)
I think you need to give us a bit more info to go on

Can you post an example question showing what calculations you've tried to do, and how/where it disagrees with the answer?
Attached Images
4. C213Jan_gkt02%5b1%5d.pdf (711.8 KB, 102 views)
5. It was k that got other calculation being not in the range and I just want to know how did they calculate this gradient
(Original post by beatrice15)
I've attached jan 2013 c2. As k I got 0.013. It is the last question on this paper. I did change in y divided by change in x.

Thank you for your help
6. (Original post by beatrice15)
It was k that got other calculation being not in the range and I just want to know how did they calculate this gradient
It's hard to say for sure because obviously when you're plotting by eye on a graph there is bound to be some subjective judgement!

I did a VERY rough estimate taking the 1st and last values for logp and for t, and got a value of 0.011506 which falls within their range, but apart from being very careful with your drawing I can't suggest anything else I'm afraid!

Good luck with the exam
7. Thank you

(Original post by davros)
It's hard to say for sure because obviously when you're plotting by eye on a graph there is bound to be some subjective judgement!

I did a VERY rough estimate taking the 1st and last values for logp and for t, and got a value of 0.011506 which falls within their range, but apart from being very careful with your drawing I can't suggest anything else I'm afraid!

Good luck with the exam

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