The answer is C and here are the steps
Answer:
or 
Step-by-step explanation:
The volume of a cylinder can be found with the following formula:

Where "r" is the radius and "h" is the height of the cylinder.
In this case, let be:
-
the volume of one of this cylinders and
the volume of the other one.
-
the radius of the first one and
the radius of the other cylinder.
-
the height of one of them and
the height of the other cylinder.
Then:

Therefore, you know this:

Simplifying, you get:

Now, knowing the ratios given in the exercise, you can substitute them into the equation:

Evaluating, you get:

It would take 5 hours for all the bacteria to die. 1000 divided by 5 is 200 so 200x5=1000
You first divide 40 by 19:
19/40=?
Then you convert that to percentage by dropping the decimal point and attaching a %
(hint: you should get 48% about :)
(144) * (x^2)
(12^2) * (x^2)
(3^2) * (2^2^2) * (x^2)
3^2 * 2^4 * x^2