Which one of the following must be true?

Abigail-Okereke on August 18, 2022


having trouble understanding why b is wrong, even after watching the real time video. can someone please help?

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Emil-Kunkin on August 21, 2022

Hi Abigail,

Let's look at our last rule, that tells us that P is after O or L, but not after both. This means that one of P/L is before O, and one is after, so we either have L...P...O, or O...P...L. We know that L is either first or last, so we can set up two scenarios.

L _ _ _ _ _ (P >O)
_ _ _ _ _ L (O>P)

In the second scenario we cannot have O be anywhere after 4, so lets look at the first.

We could try the following:


Since this could work, it is not necessarily true that two people dive after O , since O is last here, so B is not soemthing that must be true.