/*
  Lab exam 8/2/2006
  Solution Part 2
*/


public class UseVisit {

  public static double averageDuration(Visit[] ar) {
    int count = 0;
    double sum = 0;
    for (int i = 0; i < ar.length; i++)
      if (ar[i].hasTakenPlace()) {
        count++;
        sum = sum + ar[i].getDuration();
      }

    if (count == 0)
      return 0;
    else
      return sum/(double)count;
  }
}