Question

There are m persons sitting in a row. Two of them are selected at random. The probability that the two selected persons are together

• A. $\frac{{}^{m-1}{c}_2}{{}^m{c}_2}$
• B. $\frac{m-1}{m_{C_2}}$
• C. $\frac{m-3}{m_{C_2}}$
• D. $1-\frac{{}^{m-1}{c}_2}{{}^m{c}_2}$

Answer 1

The correct option is B $\frac{m-1}{m_{C_2}}$

Total ways of selecting two persons = ${}^m{C}_2$
Ways of selecting two consecutive persons = $m-1$ {taking 2 people together from no. 1 to m-1}