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A survey of 500 television viewers produced the following information, 285 watchfootball,195watch hockey, 115 watch basket ball, 45 watch football and basket ball, 70 watch football and hockey, 50 watch hockey and basketball, 50 do not watch any of the three games. The number ofviewers, who watch exactly one of the three games, is |
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Answer» 325 `=n(F)+n(H)+n(B)-n(F NNH) -n(F NN B) - n (H nn B) + n(F nn H nn B) ` `rArr 450=285+195+115-45-70-50+n(F nn H nn B)` `rArr n (F nn H nn B ) =20` n(EXACTLY one ) =`n(F)+n(H)n(B)-2n(F nn H)-2. n(H nn B) - 2. n(F nn B) + 3 n (F nn H nn B) ` `=285+195+115-2(45+70+50)+3.20` `=325` |
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