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There are 20 students in the class, four of them are being tested by the teacher. How many options are there to choose who the teacher will test?

Correct answer:

n =  4845

Step-by-step explanation:

C4(20)=(420)=4!(204)!20!=432120191817=4845  n=(420)=4845

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Showing 1 comment:
Math student
What does this question mean?  Don't all the students take all the exams?

It would make more sense if the question said: There are 20 students in the class, and every day four of them go to the library.  After how many days will all possible sets of 4 students have gone to the library together, assuming the same 4 never go together twice?

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