Galton board – Plinko probability

MathematicsProbabilityAges 13–14

Drop balls through a triangular board of pegs: each time a ball hits a peg it bounces right with probability p, and after n rows of pegs it falls into a bin at the bottom. The Intro screen drops 1, 10 or 100 balls through a fixed 12-row board with p = 0.5. The Lab screen lets you change the number of peg rows (1–26) and the probability p with sliders, drop balls continuously, and compare the experimental mean/standard deviation with the theoretical binomial formula C(n,k)pᵏ(1−p)ⁿ⁻ᵏ. Based on the "Plinko Probability" simulation by PhET Interactive Simulations, University of Colorado Boulder (CC BY 4.0); rewritten.

Lesson: Experimental and theoretical probability