Question

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

• A. 10 : 1
• B. 1 : 11
• C. 9 : 10
• D. None of these

Answer 1

Answer: (A)

10 : 1

Answer 2

$P = \frac { ( 21 ) ! 2 ! } { ( 22 ) ! } = \frac { 1 } { 11 } = \frac { 1 } { 1 + 10 }$.

∴ odd against = 10 : 1.