411 REFERENCE · Wikibooks
Puzzles/Non-scientific puzzles/Boy and Girl
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Puzzles | Non-Scientific Puzzles | Boy and Girl
thumb|Boy and Girl
A boy and a girl are talking.
"I am a boy" - said the child with black hair.
"I am a girl" - said the child with white hair.
At least one of them lied. Who is the boy and who is the girl?
Show answer
If only one of them had lied, we'd have to conclude that both are boy or both are girl. This is impossible, so both of them must have lied. Therefore, the child with the black hair is the girl, and the child with the white hair is the boy.
Show answer