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Experimental calculated values and Uncertainties

  1. Jan 15, 2013 #1
    1. After I calculated from my original data with lowest significant figure of 3, I got 0.3765 and uncertainty of 0.1274

    2.original data with lowest significant figure of 2 .calculated value of 0.69897 and uncertainty of 0.0789






    3. The attempt at a solution
    This is how I answered
    1. 0.377 uncertainty of 0.127
    2. 0.70 uncertainty of 0.01

    My teachers dosent mark our workbook so we dont know whether they are correct or not

    any help is appreciated,thank you.
     
  2. jcsd
  3. Jan 15, 2013 #2
    I use the ASTM protocol for rounding (5's round to an even number: .15 rounds up while .25 rounds down). By that rule your 0.3765 rounds to 3 sig figs as 0.376, 0.1274 rounds to 3 sig figs as 0.127, 0.69897 rounds to 2 sig figs as 0.70, and 0.0789 rounds to 2 sig figs as 0.08.
     
  4. Jan 15, 2013 #3
    Can the uncertainty be 3 significant figure?
     
  5. Jan 15, 2013 #4
    To me, it would not make sense to report an uncertainty with more than one significant figure. Additionally, it wouldn't make sense to report something like '0.377 +/- 0.1' -- because your uncertainty is in the tenths place, the hundredth and thousandth places of the measurement are pretty worthless.

    If you want a vaguely more authoritative reference, a quick google search will turn up http://www.wellesley.edu/Chemistry/Chem105manual/Appendices/uncertainty_sigfigs.html [Broken].
     
    Last edited by a moderator: May 6, 2017
  6. Jan 16, 2013 #5
    I need to to be consistent with the original data and significant figur for uncertainty need to be 1 for my answer, but I cannot follow those two because it would not make sense.does it mean that there is no correct way to report?
     
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