Find the sum and average of numbers within a limit

//pgm to find the sum and average of numbers within a limit
#include<iostream.h>
#include<conio.h>
void main()
{
    float i,a,b,sum,average;
    clrscr();
    cout<<"enter the starting number";
    cin>>a;
    cout<<"enter the ending number";
    cin>>b;
    sum=0;
    for(i=a;i<=b;i++)
        sum=sum+i;
    average=sum/((b-a)+1);
    cout<<"sum="<<sum<<endl;
    cout<<"average="<<average;
    getch();
}