Step-by-step explanation:
✰ Range : It is the simplest method or measuring the variations. A range is defined as the difference between the largest and the smallest value of distribution. If the data are arranged in ascending or descending order , then the difference between the largest and smallest values is called the range. The range is defined by :

In our case, the largest value is 21 & smallest value is 13. Plug the values :
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