Throwing a doublet — Probability Aptitude Question
Throwing a doublet: Two dice are thrown together. What is the probability of getting a doublet? Answer and worked solution on CodeKairo.
- Topic: Probability
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
Two dice are thrown together. What is the probability of getting a doublet?
Options
- 1/12
- 1/6
- 1/3
- 5/36
Show the answer and the worked solution
Correct answer: B. 1/6
Worked solution
- Doublets: (1,1), (2,2), …, (6,6) — 6 outcomes.
- Probability = 6/36 = 1/6.
Answer: 1/6.
The idea
Count the favourable outcomes directly when the sample space is small. Six doublets out of thirty-six is worth remembering.
Shortcut. Whatever the first die shows, the second must match it, which has probability 1/6 — no need to count the 36 outcomes.
Common trap. "1/3" — counting each doublet twice, as if (3,3) had a reversed order like (2,5) and (5,2); each doublet is one outcome, so 6/36.