A Straight Road Goes Through the Center of a Circular $D(r)=30-4 r$

question 66

Short Answer

A straight road goes through the center of a circular city of radius 5 km.The density of the population at a distance r (in km)from the road is well approximated by $D(r)=30-4 r$ (in thousand people per km²).Find the total population of the city, to the nearest person.