What is a simple event in probability? What is a complementary event?
A elementary event is (exactly speaking) a primary oobject which is not defined (as for example a point or a number).
More generally it is a "basic result" of a probability experiment. For example if a die is thrown the possible results (i.e. elementary events) are
A set of all elementary events is called a sample space and denoted by
An event is any subset of
A complementary event of
so the complementary event consists of all elementary events which are not in the event
I wrote earlier about an experiment of a die throw. Its sample space is (as I wrote) a set of numbers
A complementary event would be