An antique vault requires a sequence of four colored lights to be lit: Red, Blue, Green, and Yellow. Red must flash before Blue. Green cannot flash immediately after Red. Yellow must be the very last light. What is the only correct sequence?
Red, Green, Blue, Yellow
Yellow is last, leaving the first three positions for Red, Blue, and Green. Red must come before Blue. Green cannot be right after Red, so Green must be second, placing Blue third, and Yellow fourth.
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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