Four people share a birthday

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understandinguncertainty.org was produced by the Winton programme for the public understanding of risk based in the Statistical Laboratory in the University of Cambridge. The aim was to help improve the way that uncertainty and risk are discussed in society, and show how probability and statistics can be both useful and entertaining.

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I was born on my mother’s 21st birthday – 12th February 1968. A few years ago I was chatting with the elderly gentleman who lived opposite us (he has since died), and I mentioned that it was my birthday next week. “Oh really,” he said. “Which day?” “On Wednesday the 12th.” “Oh, that’s my birthday too,” he said. “Really?” I said. “What a coincidence! It’s always been a special day in our family, because it’s my Mum’s birthday as well.” “Ah yes,” he said. “Mine too.” He was quite old and a little deaf, so I thought maybe he’d misunderstood me. “No, you see I was born on my mother’s birthday.” “Yes,” he said patiently, “me too!” I had never (before or since) met another person who was born on their mother’s birthday, although I’m sure there must be quite a few around. But what are the chances of meeting someone in the same situation, whose birthday was also 12th February?
Total votes: 710
Date submitted:Sat, 14 Jan 2012 08:34:30 +0000Coincidence ID:3451