A cylindrical glass is half full of water. If you pour the water into an identical empty glass, the water level reaches the halfway mark. If you pour all the water from both glasses into a third glass with twice the cross-sectional area of the first two, what fraction of the third glass will be filled?
One-half (or 1/2)
Glass 1 is half full, meaning it contains 1 unit of water. Glass 2 is empty (0 units). Combined, you have 1 unit of water. Glass 3 has twice the cross-sectional area, meaning it requires 2 units of water to reach the same height as the first two glasses. Since you only have 1 unit of water, Glass 3 will be filled to half its height, which is one-half.
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: Medium. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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