Mode = l + (f1−f0)/(2f1−f0−f2) × h
= 40 + / × 15
Mode = 46.82
Live Figure
The modal class (cyan, f₁=20 fixed) always has the tallest bar. Raise f₀ and the mode slides left toward it; raise f₂ and it slides right — the mode always leans toward whichever neighbor is taller.