There are six professors teaching the introductory discrete mathematics class at someuniversity. The same final exam is given by all five professors. The exam score is aninteger between 0 and 100 (inclusive, that is, both 0 and 100 are possible). How manystudents must there be to guarantee that there are two students with the same professorwho earned the same final examination score?

Question

Mathematics

Michaela Duncan

20 March, 10:40

There are six professors teaching the introductory discrete mathematics class at someuniversity. The same final exam is given by all five professors. The exam score is aninteger between 0 and 100 (inclusive, that is, both 0 and 100 are possible). How manystudents must there be to guarantee that there are two students with the same professorwho earned the same final examination score?

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Lainey Owen · Answer 1

607 students to guarantee that there are two students with the same professorwho earned the same final examination score.

Step-by-step explanation:

This problem is an example of the Pigenhole principle.

The first step is finding the number of boxes and objects:

For each score, we have a box which contains the student who got that score.

If there were only one professor grading, there would need to be 101+1 = 102 students to ensure that that there are two students with the same professorwho earned the same final examination score.

However, for each student, there are a combination of six to five = 6 possible combinations for a score.

So there should be at least 6*101+1 = 607 students to guarantee that there are two students with the same professorwho earned the same final examination score.