title: extract subarray value in mongodb
body: <p>MongoDB noob here...</p>
  
  <p>I have a collection as follows...</p>
  
  <pre><code>    &gt; db.students.find({_id:22},{scores:[{type:'exam'}]}).pretty()
      {
          "_id" : 22,
          "scores" : [
              {
                  "type" : "exam",
                  "score" : 75.04996547553947
              },
              {
                  "type" : "quiz",
                  "score" : 10.23046475899236
              },
              {
                  "type" : "homework",
                  "score" : 96.72520512117761
              },
              {
                  "type" : "homework",
                  "score" : 6.488940333376703
              }
          ]
      }
  </code></pre>
  
  <p>how do I display only the quiz score via mongo shell?</p>