title: Overlaying a normal pdf onto a histogram in R
body: <p>I've looked through similar problems and I am unable to resolve mine based on what has been answered with them.  I have a histogram of Body Mass Index Data.  I have found the mean and sd of the data, and I am trying to overlay a normal pdf with the same mean and sd of the data to compare it with the histogram.  </p>
  
  <p>Here is what I have so far.</p>
  
  <p>I used hist(BMI) to graph the histogram.  I found the mean(BMI) to be 26.65 and the sd(BMI) to be 3.47.</p>
  
  <p>I am trying to use the curve function to plot a normal curve with those same parameters over the histogram.  </p>
  
  <p>curve(dnorm(x, mean = 26.65, sd = 3.47), add = T, col = "red")</p>
  
  <p><a href="http://i.stack.imgur.com/lploU.png" rel="nofollow">HistOverlay</a></p>
  
  <p>As you can see, the red curve is barely visible at the very bottom of the histogram.  Why is this error occurring?  </p>
  
  <p>Thank you.</p>