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

public class Example1{
  
  public static void Main(){

    // The average age of all females:

    double result = Person.SomePersons
       .Where(p => p.Sex == Sex.Female)
       .Select(p => p.Age)
       .Average();

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