using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var items = new []{

            new {Name="Item1", Score=2.0},

            new {Name="Item2", Score=1.0},

            new {Name="Item1", Score=2.0},

            new {Name="Item2", Score=2.0},

            new {Name="Item1", Score=3.0},

            new {Name="Item2", Score=10.0},

        };

        var groups = items.GroupBy(item => item.Name, item => item.Score);

        foreach (var group in groups)

        {

            Console.WriteLine(group.Key + ":" + group.Average());

        }

    }

}