c++ array find the average mark, highest mark, lowest mark, number of students passing,

i need help in adding the c++ code for the average mark, highest mark, lowest mark, number of students passing, using array.

01  #include<iostream>
02  using namespace std;
03  int main()
04  {
05      int gradeRange [4]= {0,0,0,0};
06      int mark = 0;
07      int counter = 0;
08   
09      while (mark < 101)
10      {
11       
12         cin >> mark;
13         if (mark > 100)
14  break;
15  if (mark >= 70)
16  gradeRange [3] ++;
17  else if (mark >= 40)
18  gradeRange [2] ++;
19  else if (mark >= 30)
20  gradeRange [1] ++;
21  else
22  gradeRange [0] ++;
23   
24  }
25  while (counter < 4)
26   
27  {
28  if (counter == 0)
29  cout << "0 - 29 ";
30  else if (counter == 1)
31  cout << "30 - 39 ";
32  else if (counter == 2)
33  cout << "40 - 69 ";
34  else
35  cout << "70 - 100 ";
36  for ( int i = 1; i <= gradeRange [counter] ; i ++)
37  {
38  cout << "*";
39  }
40  counter ++;
41  cout << endl;
42  }
43   
44  system("PAUSE");
45  }