Calculate Average of values from DataTable using LINQ and skip NULL values in C# .Net

Hi,

In my datatable i have column "mark" and corresponding values are "null, -1,null,98,0" . I need to take an average on this column. My required result is "(98+0) / 2 = 49. I wanted to neglect the null and -1 when taking average.

I can  looping through the datarow and do some tricks. Is this possbile to achieve using Linq? Any samples please