MathDB

Jane has two bags

X

and

Y

. Bag

X

contains 4 red marbles and 5 blue marbles (and nothing else). Bag

Y

contains 7 red marbles and 6 blue marbles (and nothing else). Jane will choose one of her bags at random (each bag being equally likely). From her chosen bag, she will then select one of the marbles at random (each marble in that bag being equally likely). What is the probability that she will select a red marble?

Problem Statement