MathDB

Kate has two bags

X

and

Y

. Bag

X

contains

5

red marbles (and nothing else). Bag

Y

contains

4

red marbles and

1

blue marble (and nothing else). Kate chooses one of her bags at random (each with probability

\frac{1}{2}

) and removes a random marble from that bag (each marble in that bag being equally likely). She repeats the previous step until one of the bags becomes empty. At that point, what is the probability that the blue marble is still in bag

Y

Problem Statement