A circular park of 20m diameter has a circular path just inside the boundary with a width of 1m.The are of the path is

15pi

17pi

19pi

25pi

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- Aug 19th 2008, 10:53 PMdeviCircular park
A circular park of 20m diameter has a circular path just inside the boundary with a width of 1m.The are of the path is

15pi

17pi

19pi

25pi - Aug 19th 2008, 11:00 PMChris L T521
Find the area within the park, and then subtract from that the area within the path.

So you should get $\displaystyle 400\pi-361\pi=\dots$

However, I don't see the answer as one of the choices you gave...hmmm..I'm probably overlooking something pretty obvious... (Wondering)

--Chris - Aug 19th 2008, 11:03 PMdevi
- Aug 19th 2008, 11:09 PMChris L T521
I caught my error...It had a 20 m

**diameter**...

so the area of the park would be $\displaystyle (10~m)^2\pi=100\pi~m^2$

The area of the park enclosed by the path would be $\displaystyle (10~m-1~m)^2\pi=(9~m)^2\pi=81\pi~m^2$

So then we see that the difference between the two will give us the area of the path.

$\displaystyle 100\pi~m^2-81\pi~m^2=\color{red}\boxed{19\pi~m^2}$

Does this make sense? Sorry about that; it was a mistake on my part...misread the problem.

--Chris