Margaret Bourke-White 



INTERCHANGEABLE UNITS 



However different these men and women appear, any one will do as a "medical stu- 

 dent at the University of Tiflis" in Transcaucasia 



common way of setting up norms (from a Latin word, norma, meaning 

 "a rule") is by getting the "average" of a large number of measurements or 

 counts. This number is obtained by adding all the measurements and then 

 dividing the sum by the number of individuals measured. The average is 

 a useful basis for comparison: you can say, for example, that Marion is taller 

 or shorter than the average. 



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