The Trip

I have absolutely no clue of why This one is getting a WRONG ANSWER !!!!
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Question: The Trip
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#include "iostream.h"
#include "math.h"

int main()
{
  double sum;
  float avg, arr[1000], xchg, diff;;
  int n;
  while(true) {
      cin >> n;
      if(n == 0) break;
      sum = 0;
      for(int i = 0; i < n; i++) {
          cin >> arr[i];
          sum += arr[i];
      }
      avg = sum / n;
      avg = floor(avg * 100 + 0.5) / 100;
      xchg = 0;
      for(int i = 0; i < n; i++) {
          diff = arr[i] - avg;
          if(diff > 0) xchg += diff;
      }
      cout << "$" << xchg << endl;
  }
  return 0;
}

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