title: ruby change the value of an array
body: <p>I haven't found a solution to my problem.</p>
  
  <p>I have array like this</p>
  
  <pre><code>[Thu, 01 Oct 2015 12:35:17 UTC +00:00, "10 minutes", "Successful"]
  [Mon, 06 Nov 2015 12:35:17 UTC +00:00, "8 minutes", "Successful"]
  [Thu, 01 Dec 2015 12:35:17 UTC +00:00, "6 minutes", "Failed"]
  </code></pre>
  
  <p>etc</p>
  
  <p>I want to replace "Successful" with "green", and "Failed" with "red".</p>
  
  <p>How can I achieve this?</p>