What are the chances of a message in a bottle being found and it being over 100? (Image credit: SEAN GLADWELL via Getty Images) Recently, a cheerful 100-year-old message in a bottle was found on the south-west coast of Australia. In it, a world war one soldier proclaimed to be "as happy as Larry." If you're a betting person, you probably wouldn't expect great odds of this happening. A bottle cast into the ocean could end up absolutely anywhere. So, what are the chances of a message in a bottle being found and it being over 100? And what are your chances of finding this bottle? Despite these many possibilities during a bottle's lifetime, the probability we are after is a straightforward calculation. Just count up the number of bottles with messages that have been found and are over 100 years old, and divide by the number of messages that have been sent this way (assuming we know how many are sent): Probability calculation.…