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Old Apr 10th 2017, 12:33 PM   #1
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Join Date: Apr 2017
Posts: 1
Uncertainties

Results of your chest X-ray are that you have a spherical tumor in your left lung that has a diameter of 3.4 mm, and the uncertainty is 0.4 mm. This uncertainty is the 1- sigma uncertainty based on the assumption of a normal distribution. What does this mean?

A. The tumor has a diameter between 3.0 mm and 3.8 mm.
B. There is about a 68% chance that the true diameter of the tumor lies between 3.0 mm and 3.8 mm.
C. There is about a 95% chance that the true diameter of the tumor lies between 3.0 mm and 3.8 mm.
D. The tumor has a diameter of either 3.0 mm or 3.8 mm.
E. The tumor has a diameter of 3.4 mm, but the technician may have made a mistake which makes it higher or lower by 0.4 mm.

I'd choose e, does this make sense?
cristinaclara is offline   Reply With Quote
Old Apr 10th 2017, 02:00 PM   #2
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Join Date: Aug 2010
Posts: 151
There is some error in any measurement, the fact that there is an error does not mean the technician made a mistake- I would not pick (e).

Do you know what a "normal distribution" is and what "1-sigma" means?
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