You asked this in completely the wrong way. The whole point of this riddle is that when you say "One of them is not a quarter" the listener takes this to mean that neither of them is a quarter. However by following this with "What is the other coin" you immediately undo this line of thought and the listener realises that when you said "One of them is not a quarter" you were talking about exactly one of the coins, making the solution completely trivial.
You should say "One of them is not a quarter - what are the coins?" (put the emphasis on "not" ) and then when the listener gives in you say "A quarter and a 5c, I said one of them wasn't a quarter, but the other one is - hah! fooled you" (this time the emphasis is on the first "one" ).
Originally posted by Fat LadyI like your version. Must tell my math teacher. Saying "what is the other seems to make it more confusing though.
You asked this in completely the wrong way. The whole point of this riddle is that when you say "One of them is not a quarter" the listener takes this to mean that neither of them is a quarter. However by following this with "What is the other coin" you immediately undo this line of thought and the listener realises that when you said "One of them is not a ...[text shortened]... other one is - hah! fooled you" (this time the emphasis is on the first "one" ).