The number of words are 1613 and 30817.
Work Step by Step
If a value is unusual, then it is more than two standard deviations far from the mean. $Minimum \ usual \ value=mean-2\cdot(standard \ deviation)=16215-2\cdot7301=1613$ $Maximum \ usual \ value=mean+2\cdot(standard \ deviation)=16215+2\cdot7301=30817$. The number of words are 1613 and 30817.