Suppose `n ( >=3)` persons are sitting in a row. Two of them are selected at random. The probability that they are not together is (A) `1- 2/n` (B) `2/(n-1)` (C) `1- 1/n` (D) nonoe of theseA. `1-(1)/(n)`B. `1-(2)/(n)`C. `(2)/(n+1)`D. `(2)/(n)`

Suppose `n ( >=3)` persons are sitting in a row. Two of them are selec

1.	Suppose `n ( >=3)` persons are sitting in a row. Two of them are selected at random. The probability that they are not together is (A) `1- 2/n` (B) `2/(n-1)` (C) `1- 1/n` (D) nonoe of theseA. `1-(1)/(n)`B. `1-(2)/(n)`C. `(2)/(n+1)`D. `(2)/(n)`
Answer» Correct Answer - B The total number of ways of selecting 2 persons out of n persons sitting in a row is `.^(n)C_(2)`. Number of ways in which two adjacent persons are selected from n persons sitting in a row =(n-1) Hence, required probability `=(.^(n)C_(2)-(n-1))/(.^(n)C_(2))=1-(2)/(n)`

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Suppose `n ( >=3)` persons are sitting in a row. Two of them are selected at random. The probability that they are not together is (A) `1- 2/n` (B) `2/(n-1)` (C) `1- 1/n` (D) nonoe of theseA. `1-(1)/(n)`B. `1-(2)/(n)`C. `(2)/(n+1)`D. `(2)/(n)`

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