There are eight students named Aman, Bobby, Chameli, Deepak, Ekta, Farook, Garima and Harsh in a school. They are in class 6th, 7th and 8th with no more than three students in any class.

Each of them has a favorite subject as Geography, Physics, English, Sanskrit, Maths, Chemistry, Biology and Economics not necessarily in the same order.

  1. Aman and Ekta study in same class but not with Bobby
  2. Deepak likes Chemistry and studies in class 7th only with Harsh
  3. Bobby does not study in 8th class
  4. Chameli and Farook study in the same class
  5. Those who study in class 6th do not like subject Maths or Biology
  6. Farook likes physics
  7. The one who studies in class 7th like English
  8. Chameli does not like Geography
  9. Aman's favorite subject is Sanskrit
  10. Garima does not like Biology

Can someone explain what this means: Those who study in class 6th do not like subject "Maths or Biology". Does it mean those who study in 6th standard do not like Maths and Biology both?


Those who study in the 6th class do not like both Maths and Biology is likely the correct interpretation because it leads to a unique solution.

Just make a table as follows and apply the rules. Start with the most definitive statements such as the ones about Deepak and Farook.


  • $\begingroup$ Neither the person whose favorite class is Math nor the person whose favorite class is Biology are in the 6th class. (far different from original wording but more deliberate.) $\endgroup$
    – kaine
    Jul 27 '15 at 20:37

This seems to be a question for a particular puzzle not created by yourself, so it might be hard to answer this question. Also, I think your question does not really require the puzzle to be posted but is more about general logic in such sentences.

Anyway, using strict logic, I think that the sentence

Those who study in class 6th do not like subject "Maths or Biology".

would mean being member of class 6 implies that you either don't like Maths, or don't like Biology or don't like neither.

true if (NOT M)||(NOT B)

true if (TRUE)||(FALSE)

true if (TRUE)||(TRUE)

true if (FALSE)||(TRUE)

The sentence

Those who study in class 6th do not like either the subject "Maths" or "Biology".

would mean that it implies either of the two things, but not both at the same time.

But to be honest, it is not a very clear sentence and a good puzzle would maybe be more explicit. So being confused is natural ;c). I think Len is correct what the puzzle means in this case, but requiring the puzzle-solution to be unique as an argument of interpretation of the clues is a very bad sign for the quality of the puzzle...

  • 1
    $\begingroup$ I've usually seen "they do not like either x or y" to mean that, well, they don't like either one, ie that they don't like x and they don't like y. A more formal way of stating it would be "they like neither x nor y". If they disliked only one of x and y, the phrase would be something more like "they either do not like x or do not like y". $\endgroup$
    – Zandar
    Jul 27 '15 at 6:35

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