Question

There are 2,100 bacteria in a circular petri dish. The dish has a radius of 40 millimeters. What is the approximate population density? (Use 3. 14 for π) Area of a circle = πr2 0. 02 bacteria per square millimeter 0. 42 bacteria per square millimeter 2. 39 bacteria per square millimeter 52. 5 bacteria per square millimeter.

Answer 1

B) 0.42

Explanation:

population density=number of people/square units

we plug in 2,100 for the first one but we don't know the second one for that we need the area which is A=π
`r^(2)` so the radius is 40 millimeters so
`40^(2)` =1600 1600*π=5024

2,100/5024=0.417 round it up and it is 0.42

so B) 0.42 is the answer