How many cubic yards of concrete will be needed?

Question

You're a supervisor for a project at the Fargo Airport. They want to add another runway, because Fargo is now THE tourist destination of the Midwest. The runway needs to be 16" thick to accommodate the weight of the jets. If it also needs to be 75' wide and 1.25 miles long, how many cubic yards of concrete will be needed just for the runway. Again, don't forget the 10% form variance/waste factor. You can round to the next quarter yard if you want to, but it probably won't matter on a project of this size. *

Answer 1

To calculate cubic yards, all the units for all the dimensions should be converted to yards. To multiply fractions, multiply the numerators across and the denominators across, then divide.

16 in x 1 ft/12 in x 1 yd/3 ft =

[16 x 1 x 1]/[12 x 3] = 16/36 = 0.44 yd

75 ft x 3 yd/1 ft =

[75 x 3]/[1] = 225 yd

1.25 miles x 5280 ft/1 mi x 1 yd/3 ft =

[1.25 x 5280 x 1]/[1 x 3] = 6600/3 = 2200 yd

Now these can all be multiplied together since the units are the same.

90.44 yd)(225 yd)(2200 yd) = 217800 yd³

Now for the 10% plan for waste.

217800+0.10(217800)

217800+21780 = 239,580 yd³