jQuery: Select a paragraph based on style

This is paragraph 1.

This is paragraph 2.

This is paragraph 3.

This is paragraph 4.

The Code START

<script type="text/javascript" src="./jquery-1.5.1.js"></script>
<script type="text/javascript">
      
      function stripe1() {
        $('div p.first').toggleClass("striped");
      }
      function stripe2() {
        $('div p.second').toggleClass("striped");
      }
      function stripe3() {
        $('div p.third').toggleClass("striped");
      }
      function stripe4() {
        $('div p.fourth').toggleClass("striped");
      }
</script>
<style type="text/CSS">
  <!--
    .code { color: red; }
    .back { background-color: yellow; }
  -->
</style>
  </head>

  <body>
  <h1>jQuery: Select a paragraph based on style</h1>
  <div>
  <p class="first">This is paragraph 1.</p>
  <p class="second">This is paragraph 2.</p>
  <p class="third">This is paragraph 3.</p>
  <p class="fourth">This is paragraph 4.</p>
  </div>
  <form action="">
   <input type="button" value="Stripe" onclick="stripe1()"></input>
     <input type="button" value="Stripe" onclick="stripe2()"></input>
     <input type="button" value="Stripe" onclick="stripe3()"></input>
     <input type="button" value="Stripe" onclick="stripe4()"></input>
  </form>