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Math Help - can you help please

  1. #1
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    can you help please

    a trundle wheel is used to measure distances, a person makes a trundle wheel, of diameter 40cm

    what is the circumfrence of the trundle wheel (in cms)?

    The person uses the trundle wheel to measure the length of the school car park, the trundle wheel rotates 46 times, what is the length of the car park to the nearest metre?
    and it says to use pi in all calculations
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  2. #2
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    hi

    does anyone know the answer to this?
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  3. #3
    Senior Member Peritus's Avatar
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    \begin{gathered}<br />
  D = 2r \hfill \\<br />
  P_{wheel}  = 2\pi r = \pi D \hfill \\ <br />
\end{gathered}

    Length_{school\quad car\quad park}  = 46P_{wheel}  = 46\pi D
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  4. #4
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    hi

    i still don't get it, i tried that but it doesn't seem to be working, it says the answer is wrong
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  5. #5
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    i did...

    i did pi x 40 +125.663
    and then i did 46 x 125.663 = 5026.52 and rounded it up to 5027 but it says its wrong, what have i done wrong?
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  6. #6
    Senior Member Peritus's Avatar
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    well that's because:

    46*40*pi=5780.53~5781
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  7. #7
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    oh

    but its still confusinf for me, i don't undersatnd when i do the diameter, why it doesn't work
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