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Math Help - Find the cost

  1. #1
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    Find the cost

    A local photocopying store advertises as follows. " We charge 11 cents per copy for 350 copies or less, 7 cents per copy for each copy over 350 but less than 400 , and 4 cents per copy for each copy 400 and above. " Let x be the number of copies ordered and C(x) be the cost of the job (in cents ).
    If x≤350, the cost of the copies is C(x)=_______________ cents
    If 350<x<400, the cost of the copies is C(x)=________________ cents
    If x≥400, the cost of the copies is C(x)=________________ cents
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  2. #2
    Super Member

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    Re: Find the cost

    Hello, spyder12!

    You may be able to talk your way through this problem.
    (There's one "border" where the reasoning is tricky.)


    A local photocopying store advertises as follows.
    . . "We charge 11 cents per copy for 350 copies or less,
    . . 7 cents per copy for each copy over 350 but less than 400,
    . . and 4 cents per copy for each copy 400 and above."

    Let x be the number of copies ordered and C(x) be the cost of the job (in cents ).

    If x ≤ 350, the cost of the copies is C(x) = ____ cents

    If 350 < x < 400, the cost of the copies is C(x) = ____ cents

    If x ≥ 400, the cost of the copies is C(x) = ____ cents

    \text{If }x \le 350,\text{ the cost is }\boxed{11x\text{ cents.}}


    \text{If }351 \le x \le 399,\text{ we pay }250 \times 11 \,=\,3850\text{ cents for the first 350 copies.}
    \text{Then we pay 7 cents for each copy over 350: }x-350
    \text{The cost is: }\,3850 + 7(x-350) \:=\:\boxed{1400 + 7x\text{ cents.}}


    \text{If }x \ge 400,\text{we pay 3850 for the first 350 copies,}
    \text{Then we pay 7 cents each for the next }{\color{blue}49}\text{ copies: }343.
    \text{Then we pay 4 cents for each copy over 399: }4(x-399)
    \text{The cost: }\:3850 + 343 + 4(x-399) \:=\:\boxed{2597 + 4x\text{ cents.}}
    Thanks from spyder12
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  3. #3
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    Re: Find the cost

    I don't get the second part of the question. Please explain why you would pay 250 X 11
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