Answer:
0.13 ft/min
Step-by-step explanation:
We are given that

We have to find the increasing rate of change of height of pile when the pile is 12 ft high.
Let d be the diameter of pile
Height of pile=h
d=h
Radius of pile,r=
Volume of pile=

h=12 ft
Substitute the values



Answer:

And solving for the radius we got:

And replacing the data given we got:

And this value converted to meters is 
Step-by-step explanation:
For this case we know the population size
and we also know the population density 
We can assume that the area is a circle. We also know that the formula for the population density is given by:

Where P represent the number of people and A the area. Since we are assuming a circle then the area is given by:

With X the radius of the circle
And then the populationd density become:

And solving for the radius we got:

And replacing the data given we got:

And this value converted to meters is 