[POTD] The Absent Soccer Fans

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May 21, 2015, 5:54:03 AM5/21/15
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Fanna Kansal has 30 students in his class. Out of these, 21 students are soccer fans and 9 are not.


Mr. Kansal always asks questions to randomly chosen students in his class. So, if every student is present, the probability of asking a question to a soccer fan is 21/30 = 7/10 and the probability of asking a question to a student who is not a soccer fan is 9/30 = 3/10.

One morning, Mr. Kansal notices that:
  • at least one baseball fan was absent,
  • at least one non-fan was absent; 
  • more than half of his class was present; and
  • the probability of asking a question to a soccer fan was 3/4 . 

Is there enough information to determine how many students were absent that particular morning? If yes, how many students were absent? If no, explain why not.

Note: As always, it is the solution that matters.
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