try this
Create a method in code behind to get the minutes from seconds
public string GetMinutes(object value)
{
double mins ;
double.TryParse(value.ToString(), out mins);
mins = mins / 60;
return mins.ToString();
}
change your mark up as
<asp:Label runat="server" Text='<%# GetMinutes( Eval("arrivalTime")) %>' ID="Label5"></asp:Label>