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Math Help - Simultaneous Equations

  1. #1
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    Simultaneous Equations

    Ok, I have two telephone companies, one is offering calls at 0.10p with a monthly fee of 10, the second company is offering calls at 0.20p with a monthly fee of 5.

    I am asked to create a formula using simultaneous equations, the question does not ask me to solve the equations.

    I was told to use the letter "p" for the cost of calls per month, and "n" for the number of phone calls per month.

    What I have learned so far is that the number of phone calls per month is not given, but the price per call and a monthly fee are, so based on this information I came up with the following formula.

    N = 10p + 0.10
    N = 5p + 0.20

    Do these equations seem realistic, my understanding is that N would tell me the number of calls per month, and P would tell the total cost of calls per month.

    Please advise

    Thanks

    David

    or should the equations be;

    N = 10 + 0.10p
    N = 05 + 0.20p
    Last edited by David Green; May 5th 2011 at 02:49 PM. Reason: Modify equation
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  2. #2
    Super Member Quacky's Avatar
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    Quote Originally Posted by David Green View Post
    Ok, I have two telephone companies, one is offering calls at 0.10p with a monthly fee of 10, the second company is offering calls at 0.20p with a monthly fee of 5.

    I am asked to create a formula using simultaneous equations, the question does not ask me to solve the equations.

    I was told to use the letter "p" for the cost of calls per month, and "n" for the number of phone calls per month.

    What I have learned so far is that the number of phone calls per month is not given, but the price per call and a monthly fee are, so based on this information I came up with the following formula.

    N = 10p + 0.10
    N = 5p + 0.20

    Do these equations seem realistic, my understanding is that N would tell me the number of calls per month, and P would tell the total cost of calls per month.

    Please advise

    Thanks

    David
    You've got slightly confused with your variables, I think.

    The first company charges 10 per month. For every call, you are charged an extra 0.10

    This means that for N calls, you will be charged 10 + 0.10\times N

    So p=10 + \0.10N for the first company.
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  3. #3
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    Quote Originally Posted by Quacky View Post
    You've got slightly confused with your variables, I think.

    The first company charges 10 per month. For every call, you are charged an extra 0.10

    This means that for N calls, you will be charged 10 + 0.10\times N

    So p=10 + \0.10N for the first company.
    Thanks for that information, but are you sure you don't mean; P = 10N + 0.10

    Thanks

    David
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  4. #4
    Super Member Quacky's Avatar
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    Quote Originally Posted by David Green View Post
    Thanks for that information, but are you sure you don't mean; P = 10N + 0.10

    Thanks

    David
    I don't believe I do. You have to pay 10 once every month, regardless of the number of calls used.

    It is the 0.10 which is stacking with every call.

    Also, if it was P=10N+0.10, I would hate to be the billpayer!
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  5. #5
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    Quote Originally Posted by Quacky View Post
    I don't believe I do. You have to pay 10 once every month, regardless of the number of calls used.

    It is the 0.10 which is stacking with every call.

    Also, if it was P=10N+0.10, I would hate to be the billpayer!
    OK bit of a slight problem then here?

    The equations I am given are;

    N = 10P + 0.10, N = 5P + 0.20

    N = 0.10p + 10, N = 0.20p + 5

    P = 10N + 0.10, P = 5N + 0.20

    P = 0.10N + 10, P = 0.20N + 5

    Are you sure?
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  6. #6
    Super Member Quacky's Avatar
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    Quote Originally Posted by David Green View Post
    OK bit of a slight problem then here?

    The equations I am given are;

    N = 10P + 0.10, N = 5P + 0.20

    N = 0.10p + 10, N = 0.20p + 5

    P = 10N + 0.10, P = 5N + 0.20

    P = 0.10N + 10, P = 0.20N + 5

    Are you sure?
    P = 0.10N + 10 is the same as what I have - the order has been changed, but addition is commutative, silly!
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