Exact model
A shared birthday in a room of 10
- Probability:
- 11.7%
- Odds:
- 1 to 7.6
- dBan
- −8.8 dBan
Even around a table of just 10 people, about 12 in 100 modelled groups contain a shared birthday.
Calculation
p = 1 − ∏ₖ₌₀⁹ (365 − k) / 365 ≈ 0.11694818
Assumptions
Birthdays are independent and equally spread over 365 dates. Leap days are ignored.
Sources
- Uniform 365-day birthday model