using System;
using System.Collections.Generic;
using System.Linq;

public class Example1{
  
  public static void Main(){

    // The average age of all females:

    IEnumerable<int> ages =
        from   p in Person.SomePersons
        where  p.Sex == Sex.Female
        select p.Age;

    double result = ages.Average();

   Console.WriteLine("Result = {0}", result);  // Result = 37,3333333333333
  }
}