70 bacteria are placed in a Petri dish. the conditions are such that the number of bacteria is able to double every 28 hours.
after 28 hours the number of bacteria doubles so 70*2 = 140 bacteria
Now we make a proportion
[tex]\frac{number of bacteria}{hours}=\frac{number of bacteria}{hours}[/tex]
[tex]\frac{140}{28}=\frac{x}{4}[/tex]
x = 20
Number of bacteria is increased by 20
So 70+20 = 90 bacteria
90 bacteria would there be after 4 hours
