Here from table it is clear that maximum frequency is 13 and its corresponding class is 20 - 40
So, modal class = 20 - 30
Thus, I = 20, f1=13,f0=7,f2=9 and h=10
∵ Mode =l+(f1−f22f1−f0−f2)×h
=20+(13−72×14−7−9)×10
=20+(6×1026−16)
=20+6010=20+6=26
Thus, required mode = 26