P and Q sit in a ring arrangement with 10 persons What is the probability that P and Q will sit toge...........

Quantitative Aptitude ( CCS) Probability

P and Q sit in a ring arrangement with 10 persons. What is the probability that P and Q will sit together?

2/11

3/11

2/9

4/9

n(S) = number of ways of sitting 12 persons at round table:

=(12−1)! =11!
Since two persons will be always together, then number of persons:

=10+1=11

So, 11 persons will be seated in (11−1)! =10! ways at round table and 2 particular persons will be seated in 2! ways.

n(A)= The number of ways in which two persons always sit together =10!×2
P(A)=n(A)/n(S)

=10!×2!/11!

=2/11

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