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## Tuesday, March 4, 2008

### Leap Babies

I'm sure you're aware that a year is defined as the number of days it takes for the Earth to revolve about the sun. That time is not evenly divisible into the number of hours it takes for the Earth to revolve on its axis, which is how we define the length of a day. What that all means is that instead of being exactly 365 days, a year is closer to 365¼ days.

In order to account for that extra ¼ day, we add an extra day to the calendar every four years and call that year Leap Year and the extra day is sometimes called Leap Day, which falls on February 29 in a Western calendar.

Now here's the puzzle for today: Assuming a regular birthrate, what percentage of the population celebrates their birthday on February 29?

Bon said...

0.068%?

Anonymous said...

1 / (365 + 365 + 365 + 366) * 100

100 / 1461

0.0684462696783025325119780971937029%

so bon was close. <gloat>But I was closer, so I win</gloat>.

Anonymous said...

1 in 1461 on average which in a percentage =
0.068...%

Anonymous said...

Ah, but years that are divisible by 100 are not leap years, unless they are also divisible by 400. :-) So,

97 / (365^303 + 366^97)