Monday, February 28, 2022

The chance of "just missing" at least one of two trams that come every seven minutes

Today, I just missed the tram – and then just missed one on the way back, too. That's frustrating, but the chance of missing a tram quickly increases. If "just missing the tram" means it left in the minute before you got to the stop (so you can still see it in the distance), you have a six-in-seven chance of not just missing a tram that comes every seven minutes, and the chance of not "just missing" either or both of two trams is the square of that chance – thirty-six-in-forty-nine. So your chance of "just missing" one of two trams is thirteen-in-forty-nine – over 26%. (I hope this channels my mathematician father correctly.) (Andrew Shields, #111words, 28 February 2022)

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