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Math Help - Error in Measurement Sheet. - Upper limits - HELP!!

  1. #1
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    Error in Measurement Sheet. - Upper limits - HELP!!

    Ok, I've been dumped with a maths sheet, which I don't have a clue about and I don't even know what it's about. If anyone could give me the answers and help me with the questions you don't know how much I'd appreciate it.

    1. The weights of four rowers are 86.3kg, 89.2kg, 85.0 kg and 93.9 kg.
    a) Find the upper limit of their total weight
    b) Use the answer to a) to find the maximum value of the mean weight
    c) Find the minimum value of the mean weight.

    2. A room is 3.93 m long and 2.89 m wide correct to the nearest centimetre. Find the lower and upper limits of the area of the room.

    There's alot more but could I have help on those for a starter?
    Thanks in advance.
    Last edited by ThePerfectHacker; January 21st 2007 at 11:44 AM.
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  2. #2
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    Hello, 6Brandon6!

    They are talking about Accuracy and Rounding.


    1. The weights of four rowers are 86.3 kg, 89.2 kg, 85.0 kg and 93.9 kg.

    a) Find the upper limit of their total weight

    We assume they rounded the weights to the nearest tenth of a kilogram.

    The weight of Rower #1 was given as 86.3 kg.
    His actual weight must be less than 86.35 kg.
    If his weight was exactly 86.35, it would have been rounded up to 86.4 kg.
    . . So we have: . W_1 < 86.35 [1]

    The weight of Rower #2 was given as 89.2 kg.
    . . So we have: . W_2 < 89.25 [2]

    The weight of Rower #3 was given as 89.0 kg.
    . . So we have: . W_3 < 89.05 [3]

    The weight of Rower #4 was given as 94.9 kg.
    . . So we have: . W_4 < 93.95 [4]


    Adding [1], [2], [3], [4], we have: . W_1 + W_2 + W_3 + W_4 \:< \:358.6 kg.

    Therefore, the upper limit of their total weight is 358.6 kg.



    b) Use the answer to a) to find the maximum value of the mean weight

    We have: . \frac{358.6}{4}\:=\:89.65

    Therefore, the maximum value of their mean (average) weight is: 89.65 kg.




    c) Find the minimum value of the mean weight.

    The weight of Rower #1 was given as 86.3 kg.
    His actual weight must be greater than or equal to 86.25 kg.
    If his weight was less than 86.25, it would have been rounded down to 86.2
    . . So we have:\ . W_1 \geq 86.25

    . . . . Similarly: . \begin{array}{ccc}W_2 \geq 89.15 \\ W_3 \geq 84.95 \\ W_4 \geq 93.85\end{array}

    Hence: . W_1 + W_2 + W_3 + W_4 \:\geq\:354.2


    Therefore, the minimum value for their mean weight is: . \frac{354.2}{4}\:=\:88.55 kg.

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  3. #3
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    Question

    Thanks mate.
    Had a crack at it before your post, seemed I had a rough idea. But now I know fully. Cheers again.
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