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Re: Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
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Bunuel wrote:
Each student in a class of 40 plays at least one indoor game chess, carrom and scrabble. 18 play chess, 20 play scrabble and 27 play carrom. 7 play chess and scrabble, 12 play scrabble and carrom and 4 play chess, carrom and scrabble. What is the number of students who play chess and carrom?

(A) 10
(B) 12
(C) 13
(D) 14
(E) 17


This is a PS Butler Question



Total – None = A + B + C – (A and B) – (B and C) – (C and A) + (A and B and C)

40 - 0 = 18 + 20 + 27 - 7 - 12 - (Chess and Carrom) + 4

(Chess and Carrom) = 10

Answer (A)
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Re: Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
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Bunuel wrote:
Each student in a class of 40 plays at least one indoor game chess, carrom and scrabble. 18 play chess, 20 play scrabble and 27 play carrom. 7 play chess and scrabble, 12 play scrabble and carrom and 4 play chess, carrom and scrabble. What is the number of students who play chess and carrom?

(A) 10
(B) 12
(C) 13
(D) 14
(E) 17



We can n = the number of students who play chess and carrom.

Let’s next use the following equation:

Total = chess + carrom + scrabble - sum of doubles + triple + neither

Since we do not have all the doubles we can represent the sum as n + 7 + 12 = n + 19. So, we have:

40 = 18 + 20 + 27 - (n + 19) + 4 + 0

40 = 50 - n

-10 = -n

10 = n

Ansswer: A
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Re: Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
Kavya9010 wrote:
Bunuel wrote:
Each student in a class of 40 plays at least one indoor game chess, carrom and scrabble. 18 play chess, 20 play scrabble and 27 play carrom. 7 play chess and scrabble, 12 play scrabble and carrom and 4 play chess, carrom and scrabble. What is the number of students who play chess and carrom?

(A) 10
(B) 12
(C) 13
(D) 14
(E) 17


This question can be best solve by Venn Diagram. I am attaching 2 methods to solve the same.

With warm regards,
Ks

Posted from my mobile device


Your second method is interesting, it will save considerable time. I took 2:38 mins and was looking for quicker approach.
Thanks for sharing.
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Re: Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
KarishmaB why do we add "A and B and C" but subtract all other combinations ("A and B", "B and C", etc.)? I got this wrong because I subtracted all combinations, including the "all" combination "A and B and C"
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Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
KarishmaB what a helpful link, thank you!

Originally posted by gmattyfatty on 30 Apr 2023, 21:40.
Last edited by gmattyfatty on 01 May 2023, 07:30, edited 1 time in total.
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Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
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gmattyfatty wrote:
KarishmaB why do we add "A and B and C" but subtract all other combinations ("A and B", "B and C", etc.)? I got this wrong because I subtracted all combinations, including the "all" combination "A and B and C"



Check here: https://anaprep.com/sets-statistics-thr ... ping-sets/
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Re: Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
i dont understand why tripple is being added back?

27 plus 18 plus 20 minus exactly two set minus 2 times exactly in three set should be the answer for total no?
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Re: Each student in a class of 40 plays at least one indoor game chess, ca [#permalink]
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