Question
Of the members of three athletic teams in a school, $$21$$ are in the cricket team, $$26$$ are in the hockey team and $$29$$ are in the football team. Among them, $$14$$ play hockey and cricket, $$15$$ play hockey and football, and $$12$$ play football and cricket. Eight play all the three games. The total number of members in the three athletic teams is :
A.
$$43$$
B.
$$76$$
C.
$$49$$
D.
none of these
Answer :
$$43$$
Solution :
$$\eqalign{
& n(C) = 21,\,\,n(H) = 26,\,\,n(F) = 29,\,\,n\left( {H \cap C} \right) = 14, \cr
& n(H \cap F) = 15,\,\,n(F \cap C) = 12,\,\,n(C \cap H \cap F) = 8 \cr
& \therefore n(C \cup H \cup F) = n(C) + n(H) + n(F) - n(H \cap C) - n(H \cap F) - n(F \cap C) + n(C \cap H \cap F) \cr
& = 21 + 26 + 29 - 14 - 15 - 12 + 8 \cr
& = 43. \cr} $$