Maths Problem, sorry to have to post it on AO
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Thread: Maths Problem, sorry to have to post it on AO

  1. #1
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    Maths Problem, sorry to have to post it on AO

    Hi All, I have a maths exam tommorow and I am revising, this is a question that I should be able to work out the answer to:

    Easypac Soup Company produce small cylindrical tins of radius 3cm, and similar large tins of radius 5cm. If a small tin contains 243ml of soup, how much does a large tin contain?

    Now, I think I have done the correct working to complete this question correctly. When I key that answer in on the website (BBC Bitesize Revision) it tells me that it is wrong.

    None of the other maths sites provide a question like this one so I have decided to post it on Antionline. I know that there are a lot of very intelligent people here and was really hoping that one of you could provide me with the correct answer and working out. I know that antionline is not exactly a "come here and we can answer any maths question you like" kind of site, but as I mentioned earlier, this is a very intelligent community so I thought this is where I would get the best response.

    Thanks in Advance, any help is greatly appreciated:

    Prankster
    \"Why is the bomb always gettin\' the last word?\" - Will Smith - Lost & Found (2005)

  2. #2
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    Um, I really stink at math, but can't you just divide the 243 by 3, and multiply the result by 5? Fer uh, 405ml. Eh, heh, we're dealing w/ volumns, I have no clue. . .sorry, man.
    Every now and then, one of you won't annoy me.

  3. #3
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    The volume of a cylinder is pRH where p = pi, R = radius, and H = height.

    The question suggests that the heights of both cans are equal, so we don't have to worry about that.
    Concentrate on the surface.
    The surface of the smaller cylinder: pi x 3
    The surface of the bigger cylinder: pi x 5

    Code:
    pi x 3    243
    -------- = -----
    pi x 5     Y
    
    where Y is what we need...
    I hope I don't have to tell you how to derive Y from that

  4. #4
    Jaded Network Admin nebulus200's Avatar
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    V = (PI)r^2h

    243 ml = PI (3cm * 3cm) * h

    If you use the cm and find volume you get cubic centimeters...not milliliters... 1 cm^3 = 0.001 L = 1 mL

    So with that info: 243 ml = 243 cm^3 / (3.1415 * 9 cm^2) = 8.59 cm = h

    So I am assuming that by similar they mean same height since everything else is different

    so V = (3.1415 * (5^2) * 8.59 = 675 mL

    Cheers,

    /nebulus


    PS It didn't really matter here, but always watch your units...favorite way to trip people up it seems. And always try to write down exactly what you know, and what you don't, and you will usually find that you can take what you know to figure out what you don't.
    There is only one constant, one universal, it is the only real truth: causality. Action. Reaction. Cause and effect...There is no escape from it, we are forever slaves to it. Our only hope, our only peace is to understand it, to understand the 'why'. 'Why' is what separates us from them, you from me. 'Why' is the only real social power, without it you are powerless.

    (Merovingian - Matrix Reloaded)

  5. #5
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    675 is what you get from my formula, too, so there's a big chance it's correct...Heh.

  6. #6
    Jaded Network Admin nebulus200's Avatar
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    Yeah, you beat me to it barely, but I left the post in there because it broke down how to get from point A to point B

    That was kinda fun, haven't really had much of a reason to think about that kind of stuff in a few years now...

    /nebulus
    There is only one constant, one universal, it is the only real truth: causality. Action. Reaction. Cause and effect...There is no escape from it, we are forever slaves to it. Our only hope, our only peace is to understand it, to understand the 'why'. 'Why' is what separates us from them, you from me. 'Why' is the only real social power, without it you are powerless.

    (Merovingian - Matrix Reloaded)

  7. #7
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    Thanks guys

    Thanks guys, 675 is the answer that I thought was correct answer, yet when you key 675 into the answer box, this is what you get:

    10. You said 675. Hard luck. You need to calculate the ratio of the volumes.



    I think this is pretty poor for a website coming from the BBC, as I have come to expct good service from them. Especially on an exam revision question.

    Thanks for all your help, it's really appreciated, anyway I've finished the exam now, it went OK and this wasn't even on it! Thanks Again-

    Prankster
    \"Why is the bomb always gettin\' the last word?\" - Will Smith - Lost & Found (2005)

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