Bag Contains 5 Red Marbles And 3 Black Marbles

A bag contains 5 red marbles and 3 black marbles. Three marbles are drawn one by one without … drawn be black, if the first marble is…

Answers:

Bag contains 5 red marbles and 3 black marbles, 
For atleast one of the three marbles drawn be black, if the first marble is red,
then the following situations are possible 
Event E1 = Second marble is black and third is red 
Event E2 = Second marble is black and third is also black (E2)
Event E3 = Second marble is red and third is black (E3)
Let Event Ri = drawing red marble in ith draw 
Event Bi = drawing black marble in ith draw