Challenging, Satisfying Riddles

A couple has two children. One child is a boy. What is the chance that the other child is a girl? **

Oh , one child is a boy now huh?

As there can't be 2 girls the probability of a girl is 2 chances in 3 from BG GB and BB.

Now , about my coin toss question, has the penny dropped?

I can't see it...Can you post it again?

I got this one. It's actually an old paradox.

The chance IS in fact 50% in your case - Since you said the "first" is a boy.
This means we have these cases:
Boy | Girl
Boy | Boy
- That's fifty percent.

Now, had you instead changed it to "they have two children, at least one is a boy - what is the probability that both are boys?" THEN it'd be 33% (as I'm sure you intended for it to be) as the scenarios available would then be:
Boy | Girl
Girl | Boy
Boy | Boy

- So, as sorry as I am to tell you, your wording must have messed your riddle up.

i see. anyone else have any good riddles?

I would say that riddles should be short otherwise it loses readers interest..

Another practical solution would be to use the allocated 3 seconds. Start with prisoner # 20. If asked what colour hat he is wearing the prisoner would indicate the person in front of hims colour by pre arranging the timed response. If answered immediately - inmate in front has red. If 3 second delay - inmate in front has black. #20 would have to guess his own hat though.