Question

A party of $23$ persons take their seats at a round table. The odds against two specified persons sitting together is

• A. $1$ to $11$
• B. $11$ to $1$
• C. $10$ to $1$
• D. $1$ to $10$

Answer 1

Answer: (C)

$10$ to $1$

Make the bundle of those two persons sitting together, Now we have 22 persons
$n\left(S\right)=(23-1)!$
$n\left(E\right)=(22-1)!\ast 2!$
$P=1/11$
Odds against event $E=10:1$