Friday, February 29, 2008

Happy Leap Day

This day is so rare that we should celebrate it.

I wonder if that woman who was born on Feb 29th had her baby today. The article simplistically said that only 1 in 1461 people are born on Feb 29th. The author was flashing their intelligence by realizing that the chance was 1 day in 365+365+365+366=1461. This is only true if you don't cross centuries. Since the Gregorian calendar with leap years was issued on the 24th of February, 1582 and instituted on October 15th, 1582, over the 400 year cycle the actual chance is 97 in 146,096 or slightly less than 1 in 1461. Remember that the centuries are not leap years unless divisible by 400.

The above analysis assumes that you have babies randomly, but in this day of induced births there is some choice in the matter. People tend to avoid some days and weekends, but not Leap day, apparently.

You have Pope Gregory XIII and maybe Julius Caesar before him, for not getting paid yesterday but today.


Anonymous said...

That would be 1 in 365+365+365+366 = 1461.

Richard Koehler said...

Anon, Thanks for the typo fix.