Step 1:  Search for the suitable event to the given problem

            Sure event:

            A sure event is an event, which always happens. For example, it's a sure

            event to obtain a number between “1” and “6” when rolling an ordinary die. 

           The probability of a sure event has the value of 1.

          The probability of an event that is certain to happen is 1(ONE). Such an event is called SURE EVENT