Linq groupby and count from Table List variable.

Question

List<Qry_GrandResultAttendance> lst_GrandResultAttendance = new List<Qry_GrandResultAttendance>();

 lst_GrandResultAttendanceDetails = GetGrandResultAttendanceDetails(version, session, branch, shift, _class, group, section).ToList(); 

 

  "lst_GrandResultAttendanceDetails" variable  contains below content...

 

Present	SiNo	Name	Date
1	1	a	1-1-2015
1	1	a	2-1-2015
1	1	a	3-1-2015
1	2	b	1-1-2015
1	2	b	2-1-2015
1	3	c	1-1-2015
1	3	c	2-1-2015

 

now I want that Grouping by "SiNo" and Count , As like as List<Qry_GrandResultAttendance> New_lst_GrandResultAttendance = new List<Qry_GrandResultAttendance>();

New_lst_GrandResultAttendance= lst_GrandResultAttendance.Group By (SiNo).Count......(How Linq Wrrite there), which output of "New_lst_GrandResultAttendance" below List.

Present	Si	Name	Date
3	1	a
2	2	b

   2                                         3             c