SQL Server ROW_NUMBER

Suppose there is a table Students having the columns StudName, RollNo, TotalMarks.Write a query (in SQL Server) that returns RollNo, Student Name and Total Marks along with the position (based on marks) of the students in the class.
For eg. Suppose table has following records:

The output should be

INSERT INTO [ASPState].[dbo].[Students] ([StudName],[RollNo],[TotalMarks]) VALUES ('212094', 'X', 600)
INSERT INTO [ASPState].[dbo].[Students] ([StudName],[RollNo],[TotalMarks]) VALUES ('212095','Y', 540)
INSERT INTO [ASPState].[dbo].[Students] ([StudName],[RollNo],[TotalMarks]) VALUES ('212096','Z', 580)
INSERT INTO [ASPState].[dbo].[Students] ([StudName],[RollNo],[TotalMarks]) VALUES ('212097','A', 200)
INSERT INTO [ASPState].[dbo].[Students] ([StudName],[RollNo],[TotalMarks]) VALUES ('212098', 'B', 620)

Answer
SELECT *, ROW_NUMBER() OVER (ORDER BY TotalMarks DESC) AS StudPosition FROM Students