3combo.rb

def run
  results = []

  1.upto(100000) do |i|
    results.push(rand(2))
    results.shift if results.size == 4
    if results.size == 3 && results.uniq.size == 1
      return i
    end
  end
end

trials = Array.new(10000) { run }

require 'enumerable/statistics'
p trials.max
p trials.mean_stdev
p trials.sort[trials.size / 2]
p trials.select { |n| n > 20 }.size