Chapter 9, Problem 8STP

To determine

To find: How many feet of the stone are needed.

Answer to Problem 8STP

She will need 180 square feet of stone.

Explanation of Solution

Given information:

Martha is putting a stone walkway around the garden pictured at the right.

Calculation:

Since, the shape of the garden in the given figure is of trapezoid. And the area of the trapezoid is given by

  $A=\frac{1}{2}\left(\text{Sum of the parallel sides}\right)\times \text{Height}$

From the given figure,

The parallel sides are 16ft and 20ft and height is 10ft. Therefore,

  $\begin{array}{l}A=\frac{1}{2}\times \left(16+20\right)\times \text{10}\\ A=\frac{1}{2}\times \left(36\right)\times \text{10}\\ A=36\times \text{5}\\ A=180{\text{ ft}}^2\end{array}$

Hence,

She will need 180 square feet of stone.