Override and new keyword

This example is given in the following website http://www.c-sharpcorner.com/Forums/Thread/156771/. Following code is in the program. new keyword is in question.  

public new string ToString() //Tostring() overrides the Object class version.
{
string stuString = "Student " + name + " has " + credits + " credits";
return stuString;
}

If use new keyword only without using object obj = payingStudent; why we do not get object version (Student and ScholarshipStudent). Because there is no override keyword to override object version. Problem is highlighted.

using System;

class DemoStudents4
{
public static void Main()
{
Student payingStudent = new Student();
ScholarshipStudent freeStudent = new ScholarshipStudent();

payingStudent.SetName("Megan");
payingStudent.SetCredits(15);

freeStudent.SetName("Luke");
freeStudent.SetCredits(15);

object obj = payingStudent;

Console.WriteLine(payingStudent.ToString());
Console.WriteLine(freeStudent.ToString());
Console.WriteLine(obj.ToString());

Console.ReadKey();
}
}

class Student
{
private string name;
protected int credits;

public void SetName(string name)
{
this.name = name;
}
public void SetCredits(int creditHours)//SetCredits in the child class as well
{
credits = creditHours;
}
public new string ToString() 
{
string stuString = "Student " + name + " has " + credits + " credits";
return stuString;
}
}

class ScholarshipStudent : Student
{
new public void SetCredits(int creditHours)
{
credits = creditHours;
}
}


/*
Student Megan has 15 credits
Student Luke has 15 credits
Student
*/