2002 · Q53
A and B stand in a circular ring with 10 other persons. If the arrangement of 12 persons is randomly done, the chance that there are exactly 3 persons between A and B is
General Mental Ability, Quantitative Aptitude and StatisticsNumber system and arithmetic
- A3/12
- B2/11
- C2/13
- D3/11
Explanation
Fix B's position in the circular ring; A can then occupy any of the other 11 positions. 'Exactly 3 persons between A and B' means A sits 4 places away from B on either side — 2 favourable positions out of 11. The probability is therefore 2/11 — option (B).