### Stupid code fragments, part two

Probabilities are hard. As an example, there's a known puzzle: a family has two children; if one of them is a girl, what is the probability that the other one is also a girl?The answer, un-intuitively, is

**not**1/2 but 1/3. There are various explanations but – as with the Monty Python puzzle years ago – I wanted to write code to check it out, so I wrote the following using LinqPad: void Main() { var rnd = new Random(); // Generate a random set of families with two children; true means girl, false means boy var all = Enumerable.Range(1, 10000).Select(_ => new Pair(rnd.Next(2) == 0, rnd.Next(2) == 0)).ToList(); // Extract only the families with at least one girl var oneGirl = all.Where(it => it.First || it.Second).ToList(); // Out of those families, how many have two girls? The result should be 1/3rd var otherGirl = oneGirl.Where(it => it.First && it.Second).ToList(); Console.WriteLine((decim…