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 | set theory |
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A school having 270 students provides facilities for playing four games – Cricket, Football, Tennis and Badminton. There are a few students in the school who do not play any of the four games. It is known that for every student in the school who plays at least N games, there are two students who play at least (N – 1) games, for N = 2, 3 and 4. If the number of students who play all the four games is equal to the number of students who play none, then how many students in the school play exactly two of the four games? a30 b60 c90 d120 pls show detailed sol. |
 | Re: set theory |
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ans is a 30.. let us assume no of people playing all four games be x then number of people playing at least 3, 2, 1 games will be 2x, 4x and 8x respectively number of people playing exactly 3 games = no. of people playing atleast 3 - people playing atleast 4 = 2x - x = x similarly people playing exactly two games = 4x - 2x = 2x and people playing exactly one game = 8x - 4x = 4x people playing no games = people playing all four = x so x + x + x + 2x + 4x =270 9x= 270 x=30   |
| Re: set theory |
| its 60,option b |
| Re: set theory |
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Hi rahul , What rakshit has done is absolutely correct. It is 2x the no of students who play exactly 2 games. So it is 60.  Thanks, |
| Re: set theory |
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thanx mohit, x= 30 so 2x =60 ans |
