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The arithmetic mean of 1,8,27,64, . up to n terms is given by

Options

  1. An ( n +1) 2
  2. Bn ( n +1)^2 2
  3. Cn ( n +1)^2 4
  4. Dn ^2( n +1)^2 4

Correct answer

C. n ( n +1)^2 4

Step-by-step solution

Sum of the given terms =1+8+27+64 + upto n terms Sum =1^3+2^3+3^3+4^3+ + upto n terms Sum = ( n ( n +1) 2 )^2= n ^2( n +1)^2 4 AM = n ^2( n +1)^2 4 1 n = n ( n +1)^2 4

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