Five books are stacked on a shelf from top to bottom: Chemistry, Physics, Biology, History, and Art. You pick up the Chemistry book, place it at the very bottom of the stack, and then take the top book of the new stack and place it directly beneath the Biology book. What book is now in the exact middle (third from the top) of the stack?
Chemistry.
Initial stack top to bottom: Chemistry, Physics, Biology, History, Art. Move Chemistry to bottom: Physics, Biology, History, Art, Chemistry. Top book is Physics. Place it beneath Biology: Biology, Physics, History, Art, Chemistry. The middle (third) book is History? Wait, let's re-verify. Stack: Biology (1), Physics (2), History (3), Art (4), Chemistry (5). The middle book is History. Let's trace carefully: Initial: C, P, B, H, A. Move C to bottom -> P, B, H, A, C. Top is P. Place P beneath B -> B, P, H, A, C. Third book is History. Let's adjust the question or answer. Let's make the answer History.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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