Note that Density = \(\frac{\text{population}}{\text{area}}\)

As stated in the question, there are 15 lizards, and the area of the circle that surrounds the boulder is simply \(14^2\times\pi\)or \(196\pi\)Thus the answer is \(\frac{15}{196\pi} \approx \frac{1}{41.0293333}\)