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$25$ persons are in a room. $15$ of them play hockey, $17$ of them play football and $10$ of them play both hockey and football. Then the number of persons playing neither hockey nor football is:

  1. $2$
  2. $17$
  3. $13$
  4. $3$
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Best answer
15 votes
15 votes

D. 3
No. of persons who play either football or hockey $= 15 + 17 - 10 = 22$
No. of persons playing neither hockey nor football  $= 25 - 22 = 3$

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Apply Principle of mutual Inclusion $-$Exclusion

$n(A\cup B)=n(A)+n(B)-n(A\cap B)$

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(D)3;

Explanation- number of player=25,

player who play either football or hockey=17+15,

play both hockey and football=10.

then players who play=32-10=22

then players who do not play =25-22=3;
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2 votes
no.of persons only play hockey =15-10=5
no. of persons only play  football =17-10=7
no.of persons play both hockey and football=10
so,total no of persons play hockey and football =5+7+10=22
therefore,total no. of persons neither play hockey nor football=25-22=3
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