Answer: 11
Step-by-step explanation:
The x value when everything is solved or when the all of the x's are combined?
The formula for finding area of a circle is

.
Essentially, we have two circles here. One is a larger outer circle, and the other in a smaller inner circle. In order to find the area of the sidewalk, we must find the area of the outer circle, then find the are of the inner circle. After we find both areas, we subtract.
See attached image for process of finding area, and subtracting areas to find the final area of the sidewalk.
Assuming the can is a cylinder set up the equation V=pi(r)^2h
215=pi(r)^2(7.5)
r^2=9.1248
r=3.021
Answer: The graph DOES represent a function.
Explanation: If you use a vertical line in the function and it only intersects once, that means it is a function. If it intersects twice, it is not a function.
See examples: