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  • Maths question
  • tiggs121
    Free Member

    c = b x 150 c = 200 + b

    solve for c or b

    Any takers?

    Stoner
    Free Member

    b=1.34228

    Rubber_Buccaneer
    Full Member

    You are saying b X 150 = 200 + b?

    The fact that it doesn’t come to a nice number suggests I’ve misunderstood.

    slowoldman
    Full Member

    That’s two separate equations right?

    wwaswas
    Full Member

    b=1.34228

    I kind of got there by repeated tapping of keys on calculator and doing some binary chops but it doesn’t seem to round correctly.

    Trial and error doesn’t really feel like ‘maths’ either 🙁

    GrahamS
    Full Member

    Question unclear. Do you mean:

    (c = b * 150 * c = 200 + b)

    OR

    (c = 150b), (c = 200 + b) ?

    gonefishin
    Free Member

    Trial and error doesn’t really feel like ‘maths’ either

    Iterative solutions are a perfectly valid way of solving maths problems. Assuming that they are two separate equations, then it’s just a simple set of simultaneous equations that you have to solve for both b & c.
    oh and b = 200/149 or 1.342 if you want an approximate decimal answer.

    tyrionl1
    Free Member

    1.34228 resolves it to 3 decimal places, can’t be asked to take it further got enough to do on the spreadsheet today as it is..

    Rubber_Buccaneer
    Full Member

    My second guess

    b = 1/150
    c = 200 1/150

    GrahamS
    Full Member

    If it is two equations then:

    c = 150b
    c = 200 + b

    Is the same as saying:

    150b = 200 + b

    Subtract b from both sides:

    150b - b = 200

    Which is the same as:

    149b = 200

    So

    b = 200/149 (or 1.3422818791946308724832214765101 as others said)

    Put that value of b back into one of the original equations:

    c = 150b
    c = 150 * 200/149
    c = 30000/149 (or 201.34228187919463087248322147651 in decimal)

    You can confirm by inserting both values into the other original equation:

    c = 200 + b

    30000/149 = 200 + 200/149

    30000/149 = 29800/149 + 200/149

    All Good!

    jimoiseau
    Free Member

    If they’re two separate equations, no iteration is needed.

    c= 150b
    c= 200+b

    Therefore 150b = 200+b

    150b – b = 200

    149b = 200

    b = 200/149 = 1.34228…….

    c = 200+200/149 = 201.34228…..

    edit: too late 🙁

    Stoner
    Free Member

    as gonefishin says, the exact answer is b = 200/149

    I gave the decimal for simplicity.

    Not sure why people are doing iteration in here! Have you all forgotten your algebra?! what is the world coming to?!! 🙂

    gonefishin
    Free Member

    There are times I despair of that too Stoner. A lack of basic Maths doesn’t seem to have the same stigma as a lack of good English*

    *Assuming English is your first language.

    Rubber_Buccaneer
    Full Member

    I’d still like clarification of the question, Graham S suggests two possible interpretations of what was asked.

    wwaswas
    Full Member

    A lack of basic Maths doesn’t seem to have the same stigma as a lack of good English*

    I used a calculator (well google’s one) – that makes it maths, right?

    GrahamS
    Full Member

    Graham S suggests two possible interpretations of what was asked.

    To be fair I’m pretty sure it is two equations. If it was:

    (c = b * 150 * c = 200 + b)

    Then you are saying that c = 150bc, so 150b would need to be 1, so b would just be 1/150

    Not sure if we’ll get a definitive answer from the OP.
    You are usually only allowed one or two bog breaks in an exam.

    Stoner
    Free Member

    what ^ said. I assumed that it woul dbe obvious to the OP that if c was a multiple on both sides of the equation then they would have simplified it themselves.

    therefore it made sense to assume that it was s simultaneous eq for solving.

    tiggs121
    Free Member

    It’s 2 separate equations.

    This time with a wee change

    c = b x 150

    c = 200 – b

    Stoner
    Free Member

    same method then, b = 200/151

    GrahamS
    Full Member

    c = b x 150
    c = 200 – b

    Same procedure as above really.

    150b = 200 - b
    151b = 200
    b = 200/151

    http://www.bbc.co.uk/schools/gcsebitesize/maths/algebra/simultaneoushirev1.shtml

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