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Mathematics

Predictability in Random Systems

Quick fact

A single fair coin flip is completely unpredictable, but in 1,000 flips, the proportion of heads will almost certainly be between 0.47 and 0.53 — within 3% of the expected 50%.

Why this is interesting

We often say a random event is completely unpredictable. But if you flip a fair coin 10,000 times, the total number of heads is astonishingly predictable — within about 1% of 5,000. How can something so unpredictable become so predictable?