Question

4. A circular walk has an outside diameter of 17m and an inside diameter of 15ma. Find the area of the circular walk.b. Compute the cost of constructing the walk if labor and labor and materials are estimated at a cost of Php 360 per square meter.

Answer 1

To find the area of the circular walk, we have to find the difference between the areas of the outside and inside circles:

Find the area of each circle:

$\begin{gathered} A1=\pi\cdot\frac{D^2}{4} \\ A1=\pi\cdot\frac{17^2}{4} \\ A1=226.98 \\ A2=\pi\cdot\frac{D^2}{4} \\ A2=\pi\cdot\frac{15^2}{4} \\ A2=176.71 \end{gathered}$

Now, find the difference between those areas:

$\begin{gathered} A=A1-A2 \\ A=226.98-176.71 \\ A=50.27 \end{gathered}$

The area of the circular walk is 50.27m^2.

To find the cost of constructing the walk, multiply the obtained area by the cost per square meter:

$c=50.27\cdot360=18097.2$

The cost is $18097.2.