an exact approximation (and $ V(3.02) = \frac 43 \pi
    (3.02)^3 =(36.724810\bar6)\pi$.)</p>
  </div>

  <p>We'll end this section with a problem to practice the
  example above.</p>

  <div class="problem">
    <div class="marginpar">
      Ask me in class to draw a 3D graph which illustrates the
      volume added on by each successive approximation. As a
      challenge, try to construct this graph yourself first. If you
      have it before I put it up in class, let me know and I'll let
      you share