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

The number of ways in which n ties can be selected from a rack displaying 3n different ties, is

The number of ways in which n ties can be selected from a rack displaying 3n different ties, is

Number of ways in which three numbers in AP can be selected from 1,2,3, . .,n is

Number of ways in which three numbers in AP can be selected from 1,2,3, . .,n is

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 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 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 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 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____.

Number of ways in which three numbers in A.P. can be selected from 1,2,3,..., n is