Standard deviation and average value

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  • #1
pinsky
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Homework Statement


Students measured an object 5 times, and got the results 11,25 cm, 11,20 cm, 11,22 cm, 11,18 cm i 11,25 cm. The height of this object is:

A. h = (11,22 ± 0,03) cm
B. h = (11,22 ± 0,04) cm
C. h = (11,25 ± 0,07) cm
D. h = (11,25 ± 0,03) cm

Homework Equations


Standard deviation and average value formulas.


The Attempt at a Solution



I calculated the average value (11.22) and the standard deviation (0.03), so the answer should be A. But in the book, B is the correct answer. Am I missing something here?
 
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Answers and Replies

  • #2
HallsofIvy
Science Advisor
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This question does NOT ask for standard deviation and has nothing to do with standard deviation. It is true that the average is 11,22. The largest data value, 11,25= 11,22+ ,03 but the smallest is 11,18= 11,22- 0,04. All those numbers lie in the range [itex]11,22\pm 0,04[/itex]
 
  • #3
pinsky
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Thanks, i didn't know about that.


SOLVED
 

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