2007-07-12 13:35:21 · 2 answers · asked by Big P 1 in Science & Mathematics ➔ Other - Science
Our calendar system (with leap years) has a 400-year cycle. That is, it repeats identically after 400 years. There are 146,097 days in the complete cycle, and 688 of these are simultaneously Fridays and also the 13th of the month.
So, if you are born at some random time in history, the odds of any particular day (such as your 13th or any other birthday) being a Friday and a 13th is
688 / 146,097 = 0.0047092 = 0.47092%
2007-07-12 13:54:35 · answer #1 · answered by lithiumdeuteride 7 · 2⤊ 0⤋
Pretty good!
Over any 400-year period, the 13th falls on Friday 688 times, which is more often than any other day of the week! *
The average expected lifespan at birth of all humans today is about 34, which means the vast majority of folks alive today under 13 will live past their 13th birthday.+
The odds of any particular individuals birthday being on the 13th of a month are roughly 1 in 30.
Multiply these odds together, and you will see the chance of this is FAR higher then the chance of winning the lottery!
2007-07-12 20:59:07 · answer #2 · answered by Anonymous · 0⤊ 0⤋