(iii) Ac = the event of A not happening

= the set of elements of S which are not in A

Called “the complement of A” or “A complement”

Venn diagram:

Ex: Ec= observing a number which is not even

= observing a number which is odd

= {1,3,5}

Ex: Gc= observing a number which is not greater than 4

= observing a number which is less than or equal to 4

= {1,2,3,4}

A

Ac

S