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Homework Help: Sig figs

  1. Sep 14, 2005 #1

    dnt

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    just to clarify on sig figs...for example if a question asked what is the volume of a box that is 85 m by 92 m by 95 m, the answer is 742900 m^3 but since each number has 2 sig figs, the answer must be reported as 740,000 m^3?

    is that correct?

    also, 150 has 2 sig figs but 150. has 3...right?

    thanks.
     
  2. jcsd
  3. Sep 14, 2005 #2

    NateTG

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    You've got it.
    Actually, it's probably better form to write it as:
    [tex]7.4 \times 10^{5}[/tex]
    Since that will leave no doubt about whether the zeros are significant.
     
  4. Sep 14, 2005 #3

    dnt

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    thanks.

    regarding the "150 vs 150." - i know how many sig figs it has but can someone explain WHY the decimal at the end makes the 0 significant in 150. compared to only 150?
     
  5. Sep 14, 2005 #4
    150. is read as 150.0
     
  6. Sep 14, 2005 #5

    DB

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    umm..i dont think so, i think 150.0 has four sig figs, 150. has three, and 150 two.



    dnt, the decimal in 150. is just a way of saying that, to the limits of your measuring tool, for example: this stick is exactly 150. metres , not 149, not 151, but 150.
    and in the case of 150.0, it would be implied that your measuring tool can measure to the tenth of a metre and for example you could say: this stick measures exactly 150.0 meters, not 150.1 not 150.2, but 150.0, though you know nothing about the second decimal place. it could be 150.01, 150.0[1-9], u dont know, its too precise for ur measuring tool. u get it?
     
  7. Sep 14, 2005 #6

    HallsofIvy

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    It would, of course, be better to write them as 1.5 x 102 if you intend 2 sig figures, 1.50x102 if you intend 3, 1.500x102 if you intend 4.
     
  8. Sep 14, 2005 #7
    i didnt say it IS 150.0, it is understood as 150 and nothing else. exactly 150, it has 3 significant figures.
     
  9. Sep 14, 2005 #8

    DB

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    sorry, i missunderstood ur statement
     
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