Wha'???

First off, a disclaimer: While I did study statistics in college, Probability always (and still) confused the hell out of me. BUT...

There's always a 50% chance of flipping heads. Always, on every individual flip. However, if your goal is to flip heads twice in a row, I believe the odds go down. I *think* to 25%? If you asked "what are the odds I'd flip this coin 10 times and always get heads" it'd be nearly zero. Not nearly 100%.

If Buffy was in Vegas 9 consecutive days/year, sure, you'd definitely run into her if you were there 357 days/year. But if she was there 9 times for one day each time, I don't think it'd be "guaranteed" any more -- though very close.

Help! [/b][/quote]Another precinct heard from...

The question is "How many flips does it require to guarantee at least one heads?". (You're right about getting two heads in a row being a 25% chance, but that's not the question) The answer is, "You can never guarantee it". You could flip a million times, and there is always the possibility, as infintesimal as it may be, that you get 1 million tails in a row. The more flips, the closer you get to 100%, but never get all the way there.

It's like the old problem "If you want to cross a room, and you go half the remaining distance with each step, you keep getting closer to the other side, but you never get there" The more steps you take, the closer you come to completing 100% of the distance, but you never make it all the way across.

Next.

Whether she's there for 9 consecutive days, or nine individual days, or three times for 3 days each doesn't matter. She's there nine days out of 365 days. She's not there for 356 days. So if I'm there for 357 days, the worst that can happen is that she's not there for 356 of them. But if I'm there for 357 days, there has to be at least one day when we are both there.