This question asks how many people can go at 3:00. In our setup, we saw that M and U can’t go at 3:00, because they have to go earlier than O/P and G, respectively. So, that leaves 4 as being the biggest possible answer: O, P, G, and S
Let’s see if we can put all of those at 3 pm. First, we can use diagrams from prior questions. This was from question 3:
It shows G, O and P all at or able to be at 3 pm: O and P are interchangeable. So, this proves that G, O and P can all go at 3:00.
What about S? Well, S has no ordering rules, so we can easily swap S and one of O/P. Here’s an example that obeys all the rules:
So S, O, P and G can all go at 3:00. C is CORRECT.
What I’d like you to take away from this is how to efficiently construct a diagram that lets you prove multiple things at once. Make things easy: use prior diagrams, see if you can prove that 3-4 variables work at once. Once you prove that 3 of the 4 contenders can work, focus directly on the final one.
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