Here, the maximum class frequency is 50, and the class corresponding to this frequency is 16 – 20.
So, the modal class is 16 – 20.
Now, modal class = 16 – 20, lower limit (l) of modal class = 16, class size(h) = 4
frequency (f1) of the modal class = 50
frequency (f0) of class preceding the modal class = 30
frequency (f2) of class succeeding the modal class = 40
Now, let us substitute these values in the formula