Twin sisters have twins (via daily jive) - I particularly liked this quote : "Dr. Larry Matsumoto, a physician who specializes in high-risk pregnancies, said the chances of twin sisters being pregnant with twin boys due on the same date are probably one in a million." Some highpowered probabilistic analysis there!
but it's been proven that exactly one-in-a-million chances come up nine times out of ten. (Sorry - it's that absurd, it deserves a Pratchett Paraphrase.)
Daishi
Long time lurker, I have to rely on you for my backup links, mate. Anyway, the chance is approximately one in 5.3 million, resulting in about 17.7 of these events per year. Here's my working (aint Excel wunnerful!):<br /> <br /> Population growth % 2003 -> 2004 (as per <a href="http://www.ibiblio.org/lunarbin/worldpop) 101.460%<br /> no">http://www.ibiblio.org/lunarbin/worldpop) 101.460%<br /> no</a>. of birth events / 15 years 2.029<br /> chance of 2 babies 10%<br /> chance of 2 boys 26%<br /> Days in 15 years 5,478.75 <br /> lifespan (years) 70<br /> no. females 3,240,000,000 <br /> <br /> Chance that 2 similarly aged females have a birth event on the same day 0.037%<br /> Cance that both have twins 0.000370%<br /> Cance that both sets of twins are male 0.000094%<br /> <br /> birth events / day 257148<br /> birth events / day from a twin 25715<br /> "Coincidental" birth events / day from a twin 0.048578103<br /> <br /> Chance of a birth being "coincidental" 0.000019%<br /> "One in a million" chance 0.188911126<br /> … which is equivalent to one in…. 5293494.461<br /> "Coincidental" birth events / year from a twin 17.74315212
Brendon