Question 108273: 15. Carpentry: A carpenter needs to pour a rectangular slab 28 ft. long, 16 ft. wide, and 6 in. thick. How many cubic yards of concrete does the carpenter need?
Answer by bucky(2189)   (Show Source):
You can put this solution on YOUR website! The dimensions of the rectangular slab are 28 ft by 16 ft by 1/2 ft (note that the 6 inch thickness
is equal to 1/2 foot).
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The volume of the slab is the product of these three dimensions. Therefore, the volume of the
slab is:
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28 * 16 * 1/2 = 224 cubic feet
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Each cubic yard has dimensions of 3 ft by 3 ft by 3 ft. So the volume of a cubic yard is equal
to the product of these dimensions in feet. And 3 times 3 times 3 is 27 cubic feet. Therefore,
a cubic yard of concrete is equal to 27 cubic feet.
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To find the number of cubic yards needed, divide the volume of the slab in cubic feet by
27 cubic feet in a yard. When you do you get that the Cubic Yards of Concrete (call it cyds) is:
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cyds = 224/27 = 8.296 cubic yards of concrete
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In actual practice, the carpenter would probably order 9 cubic yards of concrete. One
of those big trucks with the rotating drum holds about 10 cubic yards, and most concrete
suppliers will not deliver less than 4 cubic yards in a trip, because its not cost effective
for them. Better to waste a half cubic yard of concrete than to run short and have to
pay for another 4 cubic yards to get the truck to come. Just a little practical "real life"
thought.
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Anyhow, the answer is about 8.3 cubic yards of concrete.
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Hope this helps you to understand the problem a little better and to see how to get the
solution.
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