In the shortcut method for a 4-inch slab, the volume in cubic yards is found by dividing the circle area by which number?

In the shortcut method for a 4-inch slab, the volume in cubic yards is found by dividing the circle area by which number?

• A. 27
• B. 81
• C. 9
• D. 63

Answer: (B)

When using the shortcut method for a circular slab, you’re converting a circle’s area in square feet into a volume in cubic yards. Start by taking the circle’s area in square feet, then multiply by the thickness in feet. For a 4-inch slab, thickness is 4 inches = 1/3 foot. So volume in cubic feet is the area times 1/3. To convert cubic feet to cubic yards, divide by 27 (since 1 cubic yard = 27 cubic feet). Put together, you multiply by 1/3 and then divide by 27, which is the same as dividing by 81. Therefore, the volume in cubic yards equals the circle area (in square feet) divided by 81.

When using the shortcut method for a circular slab, you’re converting a circle’s area in square feet into a volume in cubic yards. Start by taking the circle’s area in square feet, then multiply by the thickness in feet. For a 4-inch slab, thickness is 4 inches = 1/3 foot. So volume in cubic feet is the area times 1/3. To convert cubic feet to cubic yards, divide by 27 (since 1 cubic yard = 27 cubic feet). Put together, you multiply by 1/3 and then divide by 27, which is the same as dividing by 81. Therefore, the volume in cubic yards equals the circle area (in square feet) divided by 81.