cf = Compile[{},
  Block[{part, sum1 = 0., sum2 = 0., n = 0},
   Do[
    part = RandomReal[1, 10000];
    sum1 += Total[part];
    sum2 += Total[part^2];
    n += 10000;
    ,
    {100}
    ];
   {sum1, sum2}/n
   ],
  {{sum1, _Real, 0}, {sum2, _Real, 0}, {n, _Integer, 0}, {part, _Real,
     1}}
  ]