LINQ GroupBy and select sum

Hello all,
               I have a Generic List which contains N number of rows, which is consist of
        public string CreatedDate { get; set; }
        public string MaxRange { get; set; }
        public string MinRange { get; set; }
        public string RangeDesc { get; set; }
        public string SlotName { get; set; }
        public string SlotTime { get; set; }
        public string TestAttributeDesp { get; set; }
        public Guid TestAttributeID { get; set; }
        public string TestAttributeName { get; set; }
    ...