The arithmetic mean (average) of the first n positive integers is
The arithmetic mean of nC0,nC1,nC2....nCn is (A)2^n/n (B)2^n-1/n (C)2^n/n+1 (D)2^n-1/n+1
For all positive integers n, show that
2nCn+2nCn−1=12(2n+2Cn+1)