using System; using System.Collections.Generic; using System.Linq; public class Example1{ public static void Main(){ // The average age of all females - basic version. // Uses only Select, Where and Aggregate. IEnumerable ages = Person.SomePersons .Where(p => p.Sex == Sex.Female) .Select(p => p.Age); double result = ages.Aggregate(0.0, (sum,i) => sum + i) / ages.Count(); Console.WriteLine("Result = {0}", result); // Result = 37,3333333333333 } }