You're in a hospital where your son was just born. As a nurse wheels your newborn into the nursery, she remarks that yours is the only boy in the room, and the rest of the babies are girls. Once in the nursery, boys are swaddled in blue blankets and girls are wrapped in pink.
A few minutes later, another baby is brought into the nursery and the baby's father, Tom, introduces himself to you. You couldn't see if his child was a boy or a girl, and before you get a chance to ask him, Tom has gone down the hall.
A few minutes later a baby, swaddled in blue, is brought out of the nursery.
What is the probability that Tom's newborn child is a boy?
(In reply to ....hesitating...
by Ady TZIDON)
Perhaps to assuage your reservations, extending my table might help:
Tom has nurse chose You'd see
son your baby blue
son Tom's baby blue
son other baby x pink
son other baby y pink
daughter your baby blue
daughter Tom's baby pink
daughter other baby x pink
daughter other baby y pink
In all the cases where the observed (blue) was seen,
in 2/3 of the cases Tom's baby (column 1) was a boy.
Posted by Charlie
on 2014-05-09 09:44:05