Question

What do you mean by complementary event?

Answer 1

Let S be the sample space associated with a random experiment and let E be an event. The event of non-occurrence of E is called the complementary event of E. 

It is represented by \(\bar{E}\) or E′. \(\bar{E}\) is also known as not E. 

Ex. If in a throw of a die, getting a prime number is a favourable event A, then the event of getting a number that is not prime is called the complementary event of A. 

If A = {2, 3, 5}, then \(\bar{A}\) = {1, 4, 6}