There are 2 boys and unknown number of girls in a nursery. A new baby is just born inside the room. We pick randomly a baby from the room, it turns out that the baby is a boy. What is the probability that the new baby just born is a boy?
We can solve this using Bayes' rule, as follows, P(new baby is boy | picked a boy). We end up getting 3/5. Why is this answer intuitively not dependent on the number of girls in the nursery?