title: How to create a biased number generator using a pair of six sided dice
body: <p>What is the most efficient way to use a pair of six sided dice to generate a random number in [1, 4] unevenly: it should produce 1 in 40% of the time, 2 in 30%, 3 in 20%, and 4 in 10%. </p>
  
  <p>Please justify the correctness of the method and give an algorithm. </p>
  
  <p>Dice could be of different colors.</p>
  
  <p><strong>Note:</strong> the only random number generators available are two differently coloured six-sided dice.</p>