Answer: The range of the data set is: " 16 " .
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Step-by-step explanation: 
The range is calculated by subtracting the lowest value in the given data set from the highest value in the data set.
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Given: The data set: 9, 21, 7, 11, 13, 21, 5, 14 ; 
 Let us organize these numbers from lowest value to highest value:
 " 5, 7, 9, 11, 13, 14, 21, 21 " ; 
Note: This is done by inspection. Note that all eight (8) values are accounted for.
 So, we subtract the lowest value in our given data set: "5" ; 
from the highest value in our given data set: "21" ; to get the "range":
 → " 21 − 5 = 16 " ; 
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The range is: " 16 " .
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Hope this is helpful! Best wishes!