Question

There are 135 people in a sport centre.

73 people use the gym.
59 people use the swimming pool.
31 people use the track.
19 people use the gym and the pool.
9 people use the pool and the track.
16 people use the gym and the track.
4 people use all three facilities.
How many people didn't use any facilities?

Answer 1

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Answer 2

n(U) = n(G)+n(S)+n(T)-n(GnS)-n(GnT)-n(TnS)+n(GnTnS) + n(GnTnS)^c

135= 73+59+31-19-9-16+4+ n(GnTnS)^c

no. of people not using any facility =12