Answer:
c. $660
Explanation:
The area of the arc can be computed as the product of the length of its centerline and its width. The centerline has a radius of 5.25 ft (= (4+6.5)/2) and subtends an angle of 72π/180 radians. Thus, the area is ...
(72π/180)·(5.25 ft)·(2.5 ft)
This is multiplied by the cost per square foot to get the total cost. The calculation and its result are shown in the attachment.
The cost is about $660.