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Summary: Having 3 children with the same birthday sounds like a 1/365^3 possibility, but it's actually 1/365^2, as the first can be any date, as long as the nex
by algorias 17y ago
Summary: Having 3 children with the same birthday sounds like a 1/365^3 possibility, but it's actually 1/365^2, as the first can be any date, as long as the next 2 are the same.
Add to that the amount of births per year per country, and it's not such a headline worthy story anymore.
EDIT: fixed formatting
- Retric 17y agoWTF? Where did you get 3652? Their number is calculated as 365 x 365 x 365 = 48,627,125. But in reality, of course, it’s out by an order of magnitude: one in 50 million are the odds of someone having 3 siblings sharing one particular prespecified birth date that the editors of the Daily Express sealed in an envelope and gave to a lawyer 50 years ago. In reality there is no constraint on which day the first baby gets born on, so after that, the odds of two more babies sharing that birthday are 365×365=133,225.
- tlrobinson 17y agoAnd of course that's assuming a completely random date of conception. If you try to conceive on the same date every year then it's much more likely.