Answer:
Students 3 and 4 have green discs. Students 1, 2, and 5 have red discs.
Step-by-step explanation:
If Student 1 is telling the truth, Students 2 and 3 must be lying. If that were true, Student 1 would see at least 2 red discs, not 1. So Student 1 is lying, and therefore has a red disc.
Therefore, Student 5 is also lying, and must also have a red disc.
If Student 2 is telling the truth, the other four students must be lying. That means Student 2 would have a green disc, and the other four would have red discs. But if that were true, then Student 3 would be telling the truth. Therefore, Student 2 is lying.
So far, we know Students 1, 2, and 5 are lying. If Student 3 is telling the truth, then she and Student 4 each have a green disc. If Student 3 is lying, then all five students would have red discs, which would mean Student 2 was telling the truth.
Therefore, Students 3 and 4 have green discs. Students 1, 2, and 5 have red discs.
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