<PRE><B>Question 956904</B>
there are 21 possible answers.


they range from 0 to 20.


if there are 21 students, then each student could conceivably get a different score, even though the probability of that occurring is very small.
therefore, 21 students is not enough.


it there are 22 students, then two of those students have to have the same score because there are only 21 scores to go around.


the minimum number of students required to absolutely guarantee that 2 students have the same score appears to be 22.






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