Answer:1/3
Step-by-step explanation:
This is an independent event i.e the occurrence of one does not affect the other
Finding E(Y2|Y1) means E(Y2) i.e probability that Y2 is selected if it is E(Y1|Y2), this means probability of drawing Y1.
Since this an independent event,
E(Y2|Y1) =E(Y2)
Since three balls are drawn at random, probability of drawing Y2 will be 3/9 i.e 1/3
Note that the sum total of the balls will be the total outcome.