Question

in a lab experiment, 70 bacteria are placed in a Petri dish. the conditions are such that the number of bacteria is able to double every 28 hours. how many bacteria would there be after 4 hours, to the nearest whole number?

Answer 1

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

$\frac{number of bacteria}{hours}=\frac{number of bacteria}{hours}$

$\frac{140}{28}=\frac{x}{4}$

x = 20

Number of bacteria is increased by 20

So 70+20 = 90 bacteria

90 bacteria would there be after 4 hours