Preview
Name Surname Marital status Age Birthday Employed
Joe Crosswave Married 32 1/5/1993 False
Merry Lisel Widowed 41 5/6/1983
Henry Crux Single 29 11/19/1995 True
Cody Jurut 49 8/11/1975 False
Simon Scranton Single 34 10/10/1990
Leena Laurent Divorced 19 7/1/2005 False
Ode Cosmides Married 53 4/17/1971 True
Diandra Mizner Single 20 8/20/2004 False
Pete Cassel Married 22 3/13/2002 False
Nicky Tremblay Married 32 1/5/1993 True
Mary Cassel Married 24 7/10/2000 True
Average 32
View 

@model IQueryable<Person>

@(Html
    .Grid(Model)
    .Build(columns =>
    {
        columns.Add(model => model.Name).Titled("Name");
        columns.Add(model => model.Surname).Titled("Surname");
        columns.Add(model => model.MaritalStatus).Titled("Marital status");

        columns.Add(model => model.Age).Titled("Age");
        columns.Add(model => model.Birthday).Titled("Birthday").Formatted("{0:d}");
        columns.Add(model => model.IsWorking).Titled("Employed");
    })
    .UsingFooter("_GridFooter")
)
_GridFooter partial view 

@model IGrid<Person>

<tr>
    <td colspan="3"><b>Average</b></td>
    <td><b>@(Model.Rows.Average(row => row.Model.Age))</b></td>
    <td></td>
    <td></td>
</tr>