SOLUTION
We want to find which region has a population less than 60 animals in the diagram below
Population desity is calculated as
[tex]\text{Population density = }\frac{\text{ number of animals }}{\text{area of region }}[/tex]
So let's get the areas of triangles A, B, C, and D we have
[tex]\begin{gathered} \text{area of triangle =}\frac{1}{2}\times base\times\text{height} \\ A=\frac{1}{2}\times40\times35=700m^2 \\ B=\frac{1}{2}\times50\times38=950m^2 \\ C=\frac{1}{2}\times49\times42=1,029m^2 \\ D=\frac{1}{2}\times32\times51=816m^2 \end{gathered}[/tex]
Population density for each becomes
[tex]\begin{gathered} \text{Population density = }\frac{\text{ number of animals }}{\text{area of region }} \\ \text{For A = }\frac{\text{ 42500 }}{\text{700 }}=60.714\cong61\text{ animals } \\ \text{For B = }\frac{60800}{950}=64\text{ animals } \\ \text{For C = }\frac{57300}{1029}=55.685\cong56\text{ animals } \\ \text{For D = }\frac{49200}{816}=60.29\cong60\text{ animals } \end{gathered}[/tex]
Region C has a population density of 56 animals per square mile, which is less than 60.
Hence the answer is region C, option C
