Let `P_n` denotes the number of ways in which three people can be selected out of 'n' people sitting in a row, if no two of them are consecutive. If `P_(n+1)- P_n=15` then the value of 'n` is____.

Let N denotes the number of ways in which 3n letters can be selected from 2n A's, 2nB's and 2nC's. then,

Let P_(n) denotes the number of ways of selecting 3 people out of 'n' sitting in a row, if no two of them are consecutive and Q_(n) is the corresponding figure when they are in a circle. If P_(n) – Q_(n) = 6, then 'n' is equal to

Let P_n denotes the number of ways of selecting 3 people out of n sitting in a row, if no two of them are consecutive and Q_n is the corresponding figure when they are in a circle. If P_n- Q_n= 6, then 'n' is equal to 7 (B) 8 (C) 9 (D) 10

prove that total number of ways of selection of r points out of n points in a row such that no two of them are consecutive C(n-r+1,r)

If (p/q)^(n-1)=(q/p)^(n-3) , then the value of n is

If ^(2n+1)P_(n-1):^(2n-1)P_(n)=3:5, then find the value of n.

No of ways if r people out of N people will not be consecutive in circle.