Solution:
Intersection ( Ω ) are elements you can find in both sets.
n in n(A∩B) means the number of elements. So you count how many elements are in A∩B once you are done finding the elements.
A={1,3,5,7,9,11,13,15}
B={3,6,9,12,15}
As you can see 3,9 and 15 are the only elements that can be seen in both the sets A and B
Hence A∩B={3,9,15}
Since you are asked how many elements ( n ), you count how many elements are in {3,9,15} and I believe you've counted three
Hence n(A∩B)=3
© africaexams.com