Question

(d) Given that n(§) = 96, n(A) = 50 and n(B) = 60. Find the maximum and minimum values for n(An B).

Answer 1

Step-by-step explanation:

the max. value is when the smaller set (A) is completely contained in the larger set (B).

then n(A n B) is n(A) = 50.

the set intersection between A and B cannot get bigger than that. or A gets bigger ...

after all, the intersection means it is a set of all elements that exist in BOTH sets.

but then there must be other elements besides A and B in the universal set too, because n(universal set) = 96, and n(A u B) would be only 60.

the min. value could be the empty set or 0. but because n(universal set) = 96, and n(A) + n(B) = 110 and larger than 96, it means that there have to be some shared elements. at least 110 - 96 = 14 elements.

in this case there cannot be other elements in the universal set than A and B. and n(universal set) = n(AuB) = 96.