C Sharp :: Linq - How To Group Values Week Wise And Store In Another Datatable

I have a datatable which comprises values from 1st January to march, something like this:

DataTable datatable = new DataTable("Employee");
datatable.Columns.Add("Date", typeof(string));
datatable.Columns.Add("Employee", typeof(string));
datatable.Columns.Add("Job1", typeof(double));
datatable.Columns.Add("Job2", typeof(double));  
datatable.Rows.Add(new Object[] { "1/4/2013", "A", 1.3, 2 });

[Code] ....

The result should look like this for Job1:

Employee 1/7-1/13 1/14-1/20 1/21-1/27 1/28-2/3 and so on...
A sum of values for this 7 days
B
C
D

I want to add all the values of Job1 for each employee in a time range which is one week starting from monday to sunday. How can I group the Job1 values week wise and store them in another datatable.