This is the source code to calculate the average of all the values in the array
#include<iostream.h>
#include<conio.h>
main()
{
int A[5]={3,6,9,12,15};
int sum;
float average;
sum=A[0]+A[1]+A[2]+A[3]+A[4];
average=sum/5;
cout<<"Average="<<average<<endl;
getch();
}
End