So the birthday paradox is where if you’re in a room with 23 other people there’s a 50% chance of at least two people having the same birthday. Alternatively, In a room of 75 there’s a 99.9% chance of at least two people matching.
Why is this?
In: 134
If it’s JUST TWO people in a room, there is a 1:365 chance they have the same birth day. You have ONE chance to match birth days.
If there are THREE people in the room, there is a 1:365 chance first person has the same birth day as the 2nd person. There is a 1:365 chance they have the same birth day as the second person. There is a 1:365 chance that the second person matches the third person.
Adding ONE PERSON means that there are THREE times as many chances to hit that rare probability and its 1:365 + 1:365 + 1:365 not 3:365 (these are very different in probability)
If you add a 4th person your have 12 chances for the probability.
If you add a 5th person you have 20 chances for a match
6th person 30 chances for a match
7th person 42 chances
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