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If an=sum(r=0)^n1/(^n Cr) , then sum(r=0...

If `a_n=sum_(r=0)^n1/(^n C_r)` , then `sum_(r=0)^n r/(^n C_r)` equals `(n-1)a_n` b. `n a_n` c. `(1//2)n a_n` d. none of these

A

`(n-1)a_(n)`

B

`na_(n)`

C

`1/2na_(n)`

D

None of these

Text Solution

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The correct Answer is:
C
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