Question

S. A and B stand in a ring with 11 other persons.
If the arrangement of the 13 persons is at
random, then the probability that there are
exactly 3 persons between A and B is:
​

Answer 1

Answer:

hola q te pasa enviando eso xdxdxd

Answer 2

Answer:

Final Answer.

Step-by-step explanation:

Explanation:

Standing 13 persons around a circle can only be done in 12! ways. We need to consider a group of 5 people, comprising of A & B sandwiching 3 other random people, who can be chosen in 11C3 ways. This group, being a linear segment of the circle, can be arranged internally in 2X3! ways and with 11C3 ways of grouping we have 11C3x2x3! arrangements. Now consider circular seating of this group along with 8 other remaining people, totally 9 entities. The number of ways will be 8!x11C3x2x3!. Now the probability, as requested, would be (11C3x8!x2x3!)/12! = (165x2x6)/(9x10x11x12) = 165/990 = 1/6

Therefore, the correct answer is 1/6.

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