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Help Needed - Practice Problem!

  1. Oct 3, 2006 #1
    For a sample of 100 wheat fields, the mean yield was 10 tons/acre and the standard deviation 2. Approximately how many fields out of the 100 should have yields in the 8 to 12 ton range? Show work.
     
  2. jcsd
  3. Oct 3, 2006 #2

    CRGreathouse

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    What have you figured out so far?
     
  4. Oct 4, 2006 #3
    I'm hoping the answer is 68. I don't understand at what point you differentiate betwen multiplying by 95.4% or 68.3%.
     
  5. Oct 4, 2006 #4

    CRGreathouse

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    68.3% the the area under the normal curve within 1 standard deviation; 95.4% is the area under the normal curve within 2 standard deviations.

    Since the question gives you 1 standard deviation in either direction, your answer is correct. 95 fields would be the correct answer if they asked for the numbr with 6 to 14 tons.
     
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