title: How to insert randomly entries of an array in another array
body: <p>Let's says I have this array :</p>
  
  <pre><code>$numbers = array(1,2,3,4,5);
  </code></pre>
  
  <p>And this array :</p>
  
  <pre><code>$letters = array('A','B','C');
  </code></pre>
  
  <p>I want to put <code>$letters</code> entries inside <code>$numbers</code> randomly. I don't care about the order of <code>$letters</code>, but I want <code>$numbers</code>to keep the order. The goal is to have this kind of array :</p>
  
  <pre><code>$randomLettersInNumbers = array(1, 'B', 2, 3, 'A', 4, 'C', 5);
  </code></pre>
  
  <p>How can I achieve this ?</p>