The formula of the volume of a cylinder:

We have:

and

substitute:
Answer: The area of a base of the cylinder is equal 45 dm².
Answer:
Calvin will paint the entire area in 92 minutes or 1 hour 32 minutes.
Step-by-step explanation:
First of all we know that the total surface are that Calvin is painting is 115 square feet.
The rate at which Calvin is painting refers to the surface area he covers every 2 minutes. This is 2.5 square feet every 2 minutes.
we can set up a relation to solve this problem
If Calvin paints
in 2 minutes
He will paint
in
minutes
By cross multiplying, we have 
Hence Calvin will paint the entire area in 92 minutes or 1 hour 32 minutes.
The 2nd one or either the last one, I suggest the last one hope this helps!!
Answer:
64 people/m^2
Step-by-step explanation:
The population density can be found by diving the number of people by the amount of area
I assume that the answer should be in metre squares or the area should be 1.95 million km^2
124000000/(1.95*1000000)
=63.5897...
=64 people/m^2