If n>=2 then the number of surjections that can be defined from {1 2 3......n} onto {1 2} is (1) n^(2)-n (2) n^(2)

If A={1,2,3,.....n],nge2 and B={a,b} , then the number of surjections from A to B is

Number of ways in which three numbers in A.P. can be selected from 1,2,3,..., n is a. ((n-1)/2)^2 if n is even b. n(n-2)/4 if n is even c. (n-1)^2/4 if n is odd d. none of these

Let A={1,2,..., n} and B={a , b }. Then number of surjections from A into B is nP2 (b) 2^n-2 (c) 2^n-1 (d) nC2

Let A={1,2,..., n} and B={a , b }. Then number of surjections from A into B is nP2 (b) 2^n-2 (c) 2^n-1 (d) nC2

Two players P_1a n dP_2 play a series of 2n games. Each game can result in either a win or a loss for P_1dot the total number of ways in which P_1 can win the series of these games is equal to a. 1/2(2^(2n)-^ "^(2n)C_n) b. 1/2(2^(2n)-2xx^"^(2n)C_n) c. 1/2(2^n-^"^(2n)C_n) d. 1/2(2^n-2xx^"^(2n)C_n)

The total number of ways of selecting two numbers from the set {1,2, 3, 4, ........3n} so that their sum is divisible by 3 is equal to a. (2n^2-n)/2 b. (3n^2-n)/2 c. 2n^2-n d. 3n^2-n

The arithmetic mean of 1,2,3,...n is (a) (n+1)/2 (b) (n-1)/2 (c) n/2 (d) n/2+1

The arithmetic mean of 1,2,3,...n is (a) (n+1)/2 (b) (n-1)/2 (c) n/2 (d) n/2+1

When a transition of electron in He^(+) takes place from n_(2)" to "n_(1) then wave number in terms of Rydberg constant R will be ("Given "n_(1)+n_(2)=4, n_(2)-n_(1)=2)

The mean deviation of the series a , a+d , a+2d ,.....,a+2n from its mean is (a) ((n+1)d)/(2n+1) (b) (n d)/(2n+1) (c) (n(n+1)d)/(2n+1) (d) ((2n+1)d)/(n(n+1))