For a slab measuring 16 feet by 20 feet and 4 inches thick, how much concrete should be ordered?

• A. 3.0 cubic yards
• B. 3.5 cubic yards
• C. 4.0 cubic yards
• D. 5.0 cubic yards

Answer: (B)

To determine the amount of concrete needed for a slab measuring 16 feet by 20 feet and 4 inches thick, we first need to calculate the volume of the slab in cubic feet.

1. Convert the thickness of the slab from inches to feet. Since there are 12 inches in a foot, 4 inches converts to:

[

\text{Thickness in feet} = \frac{4 \text{ inches}}{12 \text{ inches/foot}} = \frac{1}{3} \text{ feet} \approx 0.3333 \text{ feet}

]

2. Calculate the volume in cubic feet using the formula for the volume of a rectangular prism (Volume = length × width × height):

[

\text{Volume} = 16 \text{ feet} \times 20 \text{ feet} \times \frac{1}{3} \text{ feet} = 16 \times 20 \times 0.3333 \approx 106.67 \text{ cubic feet}

]

3. Since concrete is ordered in cubic yards, we need to convert cubic feet to cubic yards. There are 27 cubic feet in a cubic