Question

A biologist is studying a plant blight. At the start of their research, the blight covers a circular area with a radius of 5 kilometers. When they re-examine the blight two years later, the area has grown to a circular area with a radius of5.2kilometers. How rapidly did the radius change over the interval? _____Year/km

Answer 1

Explanation:

Area of circle 1= pie r²

=3.14 x 5²

=3.14x 25

= 78.5km²

Area of circle 2=3.14 x 5.2²

= 3.14 x 27.04

= 84.9km²

change in area= 84.9-78.5

=6.4

radius²= 6.4/ 3.14

r²=2.03

r =√2.03

r=1.42