I am not sure I understand your question. Can you explain?

It is an inclusive series First convert inlt into exclusive series.

​@@Biostatisticsthe data in the video is not continues so the correct range is 21

@@user-lr6kp8ns7x you have a point but don't forget there are several ways to compute the range for grouped frequency distributions, these methods produce different results because we don't have the actual value and so the methods tend to estimate the range. This method I used is the simplest, I will cover other methods in another video.

@@Rois677 Yes that's another method but don't forget that there are several different methods. Though these methods give different answers they are accurate cos they are only estimations of the actual range. The true range cannot be known since we don't have the individual data values.

Lemon Squeezy