T3B10

Answer to T3B7:

The coins were fake. BC stands for Before Christ, so how could people know it was 400 years before Christ was born? The dating system of BC and AD arose some years after Christ's birth. (oh look! geeky fact!)

Answer to T3B8:

I don't really understand this, now that I read it more carefully...

The back prisoner will yell "black" if there is an odd number of black hats in front of him and "white" if there is an even number of black hats in front of him. The next prisoner will then count the number of black hats in front of him and if it was odd and is now even, or vice versa, then that person knows what color their hat is. The next person then knows their hat color based on what the people before them said and how many black hats are in front of them. In this way the front 99 prisoners will know their hat color and will be set free. The prisoner in the back who goes first has a 50 percent chance of being set free.

I just realized, what if you have, say 98 black hats in front of you and 1 white? And you have a black hat? Then you'd have to say "white" but you'd go to jail! And if the next person saw 97 black hats and 1 white, then he'd know he was a black hat. But he'd say "black" because... oh, I get it now.

Okay wait, what if you see 97 black hats and 2 white ones? You have a white hat, and you say "black". You go to jail. The next person sees 96 black hats and 2 white ones. He has a black hat. He says "white" and also goes to jail! The next person sees, say, 96 black hats and 1 white one. He says, "white". The next person sees 95 black hats and 1 white one. He says, "black".

Then you can only save 98!

Or if you have the same circumstances, but the second person sees 97 black hats and 1 white one? He has a white one, but has to say "black". The next person person sees 97 black hats and no white ones. He says "black" but knows he's white, and he has to go to jail! The next person sees 96 black hats and no white ones. "White", but he's wrong! This way, less than 50 people will be saved, because each person will have to alert the person in front of them and it will alternate--white, black, white, black. But they're all black....

I'm very confused now. Even after this long and crazy rant about this riddle. :(

I'll post the answer to T3B9 tomorrow... leave some more time to think... :P