Question

38. A concrete sidewalk is to be built (as shown in Illustra-

tion 2) around the outside of a corner lot that measures
140 ft by 180 ft. The sidewalk is to be 5 ft wide. What is
the surface area of the sidewalk? The sidewalk is to be
4 in. thick. How many yards (actually, cubic yards) of concrete are needed? concrete costs $90/yd^3 delivered. How much will the sidewalk cost?

Answer 1

($90/yd^3) to get the total cost.

Explanation:

To calculate the surface area of the sidewalk, first, find the area of the larger rectangle formed by the outer boundary of the sidewalk. Then, subtract the area of the smaller rectangle formed by the inner boundary of the sidewalk.

Surface Area of the Sidewalk:

Area of the larger rectangle = (140 + 2 * 5) * (180 + 2 * 5) square feet

Area of the smaller rectangle = 140 * 180 square feet

Surface area of the sidewalk = Area of the larger rectangle - Area of the smaller rectangle

Volume of Concrete Needed:

The thickness of the sidewalk is given as 4 inches, which is equal to 4/12 feet.

Volume of concrete needed = Surface area of the sidewalk * Thickness of the sidewalk

Convert the volume of concrete into cubic yards:Since 1 yard = 3 feet, there are 27 cubic feet in 1 cubic yard.Number of cubic yards of concrete needed = Volume of concrete needed / 27Cost of the Sidewalk:Multiply the number of cubic yards of concrete needed by the cost per cubic yard ($90/yd^3) to get the total cost.I can calculate these values for you if you provide the necessary information or if you want to confirm your calculations.