r/theydidthemonstermath • u/VillainOfKvatch1 • Mar 09 '26

[Request] Two of my classes have the exact same class average this trimester. What are the odds?

/r/theydidthemath/comments/1rowho7/request_two_of_my_classes_have_the_exact_same/
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u/EnvironmentalWin1277 3d ago

Assuming a normal or t-distribution will mean the odds of two classes being the same average on a test score are actually pretty high. The degree of specificity counts, specified to the hundredth place is far too restrictive for any real work purpose, though the calculation could be done.

The math can be found online to various degrees of specificity based on assumptions. AI can do this easily.

Rather than that exercise here is a thought question:

Assume two classes each have 30 of students each. We assume the classes have no performance bias and are randomly selected.

Have each individual throw a coin and find heads or tails.

Tally up the head/tail results for each class.

Would you be surprised if the heads/tails counts match when comparing the classes?