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Homework Help: Easy operations but somehow I'm wrong

  1. Dec 8, 2008 #1
    1. The problem statement, all variables and given/known data
    Carry out these operations as if they were calculations of experimental results, and express each answer in the correct units and with the correct number of significant figures:
    (d) (7.8 m - 0.34 m) / (1.15s + 0.82 s)

    2. Relevant equations

    3. The attempt at a solution
    (7.8 m - 0.34 m) / (1.15 s + 0.82 s)
    (7.46 m) / (1.97 s)
    3.79 m/s

    It tells me the answer is 0.76 m/s :\. I double checked and this is what they say is the right answer.
  2. jcsd
  3. Dec 8, 2008 #2


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    Science Advisor
    Homework Helper

    I think you misunderstood the question, the second number is the uncertainty on the first.
    So the question is 7.8m/1.15s and then from the uncertainty in the values you are given decide how many figures you are justified in using in the answer.
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