The bean machine, also known as the quincunx or Galton box, is a device invented by Sir Francis Galton to demonstrate the central limit theorem, in particular that the normal distribution is approximate to the binomial distribution.
The machine consists of a vertical board with interleaved rows of pins. Balls are dropped from the top, and bounce left and right as they hit the pins. Eventually, they are collected into one-ball-wide bins at the bottom. The height of ball columns in the bins approximates a bell curve.
Overlaying Pascal's triangle onto the pins shows the number of different paths that can be taken to get to each bin.
A large-scale working model of this device can be seen at the Museum of Science, Boston in the Mathematica exhibit.
Read more about Bean Machine: Distribution of The Balls, Games
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