Conditional probability · Board games · difficulty 2 of 5
Which die was it?
A bag holds two fair dice: an ordinary 6-sided die and a 20-sided die numbered 1 to 20. You pick one of the two at random, with equal chance, and roll it once without looking at which one it is. It shows a 5. What is the probability that you rolled the 6-sided die?
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