Can You Solve The Newborn Baby Probability Puzzle?

Time to dust off those probability math skills you sharpened in high school: this is a hard one. It's the probability puzzle presented by Presh Talwalkar of the MindYourDecisions YouTube channel that he says has been asked as an interview question. Here's the problem: On the morning of January 1, a hospital nursery has 3 boys and some amount of baby girls. That night, a child is born and is placed in the same nursery along with the other babies. On January 2, a child is selected at random from the nursery. The child is a boy. What is the probability the child born on January 1 was a boy? Get the answer by watching the video below, or by scrolling down to read the answer. Good luck!

Can You Determine The Probability That The Newborn Is A Boy?

You want a tough problem? Here ya go.


There is a 50.5% chance the child born on January 1 was a boy. Watch the video above to learn why.

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Written by Curiosity Staff November 21, 2016