There are 2,100 bacteria in a circular petri dish. The dish has a radius of 40 millimeters. What is the approximate population density? Area of a circle = 3.14r2

Answer: 0.42 bacteria/mm^2

Step-by-step explanation: Population density is population / area. First we solve for the area of the circle. A = pi•r^2. r = 40 mm. pi • 1600 = 5024mm^2. Divide the 2100 bacteria by 5024 and you get population density. 2,100/5024 = 0.42 (rounded to two decimal places)