Question

In the figure below, a circular swimming pool (the unshaded area) is surrounded by a circular walkway (the shaded area). Both the circular swimming pool and the entire circular region consisting of the swimming pool and the walkway have the centre O. If the radius of the swimming pool is 10 meters and the width of the walkway is 5 meters, how much greater than the surface area of the swimming pool is the area of the walkway?

• A. 100$\pi$
• B. 50$\pi$
• C. 25$\pi$
• D. 125$\pi$

Answer 1

Answer: (D)

125$\pi$

Answer 2

Area of circle $=\pi r^2$
radius swimming pool = 10
radius walkway = 15
$\pi15^2-\pi10^2=225\pi-100\pi=125\pi$
The correct option is (D): 125$\pi$