Density is the measurement of the amount of mass per unit of volume.
In this case we should calculate the density of prairie dog burrows on a square field. This is a surface charge density.It is defined as the total amount of units q per km^2.
to calculate the density of prairie dog burrows, we should divide the total number of prairie dog burrows in the field by the size of the field. Thus,
prairie dog burrows in square kilometers= number of dog burrows/ size of the field
size of the field=0.9*0.9=900*900=180000m^2
1980/180000 m^2= 0.011 dog burrows in square meter
11 dogs in square kilometer
