Conditional probability · Urn · difficulty 2 of 5
Which urn am I drawing from?
Urn A holds 3 red balls and 1 blue ball. Urn B holds 1 red ball and 3 blue balls. A fair coin flip picks one of the urns and you don't know which. You draw 2 balls from it at random, putting each ball back and mixing before the next draw, and all of them are red. What is the probability you're drawing from urn A?
Answer with a probability. First lock in a gut guess with an 80% range, then solve it properly, then watch a simulation settle on the truth.
More conditional probability puzzles
- A six is showing · Board games
- At least one boy · Family
- At least one red card · Playing cards
- The flagged transaction · Fraud detection
- The host knows · Game show
- Three boxes, one gold coin · Antique shop
All conditional probability puzzles · All puzzles · Market making game