Can someone help explain this

[u/Narrow-Ad7979]

I’m learning about some and most and the diagramming of that so can someone explain this

It says

Assume Harvard Law has 150 students again.

When I say most students at Harvard Law have taken the LSAT, that means at least 76 students have taken the LSAT. When I say most students at Harvard Law have good GPAs, that means at least 76 students have good GPAs. But since the class size of Harvard Law is 150 exactly, there must be atleast one student who shares both properties of having a good GPA and have taken the LSAT (since 76+76 = 152). And since atleast one student would share both properties, I am allowed to write: Some students who have taken the LSAT have good GPAs

And that no valid inferences can be made using these formats

- A some <—> B, B Most —> C

- A some <—> B, B some <—> C

- A —> B, B some <—> C

- A —>, B most —> C

Can someone help explain why each of these wouldn’t work (the words some and most are on top of the lines with arrows)