If `a_n=sum_(r=0)^n1/(nC_r),` then `sum_(r=0)^n r/(nC_r)` equals

If a_n=sum_(r=0)^n1/(""^nC_r) , then sum_(r=0)^nr/(""^nC_r) equals :

If a_n=sum(r=0)^n 1/^nC_r, then sum _(r=0^n r/^nC_r equals (A) (n-1)a_n (B) na_n (C) 1/2na_n (D) none of these

If a_(n)=sum_(r=0)^(n)(1)/(nC_(r)), then sum_(r=0)^(n)(r)/(nC_(r)) equals

If S_n=sum_(r=0)^n 1/(nC_r) and t_n=sum_(r=0)^n r/(nC_r), then t_n/S_n=

If s_n= sum_(r=0)^n 1/(^"nC_r) and t_n=sum_(r=0)^n r/("^nC_r) then t_n/s_n is equal to

If s_n=sum_(r=0)^n1/(""^nC_r)and t_n=sum_(r=0)^nr/(""^nC_r), then t_n/s_n is equal to :

If S_(n)=sum_(r=0)^(n)(1)/(nC_(r)) and sum_(r=0)^(n)(r)/(nC_(r)), then (t_(n))/(S_(n))=

If a_(n)=sum_(r=0)^(n)(1)/(""^(n)C_(r)) then sum_(r=0)^(n)(r)/(""^(n)C_(r)) equal to

If (1+x)^n=sum_(r=0)^n .^nC_r x^r then sum_(r=m)^n .^rC_m is equal to