Unit 14 · Ordering Deduction
Izzy, Caitlin & Melissa — Which Step Is Impossible?
Lesson 4 of 6
About this lesson
Ordering problems do not always come as a list of finish positions. This one involves heights and stairs — and the key insight is that a staircase works like a measuring scale in reverse: taller people go on lower steps, shorter people go on higher steps, so everyone's head reaches the same level. Once you see that, the "impossible" option stands out immediately.
Chapters
Question
Izzy is taller than Caitlin; Caitlin is shorter than Melissa.
But when they stand on a short flight of three stairs, one on each step, their heads are all level.
Which one of these sentences cannot be true?
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