Quandaries and Queries


I have a carport that is 20' x 31' and a driveway that is 12' x 18' that requires a 3" depth of concrete.
I need to now how many cubic yard it will need to complete these two areas. Thank you.

My grade level is 9th
I am requesting an answer from a teacher.



Hi Cyndi,

You have two rectangular slabs of concrete, one of them 20' by 31' by 3" and the other 12' by 18' by 3". The volume of a rectangular solid is the length times the width times the height, however you want the volume in cubic yards and the dimensions are in feet and inches. You should first convert all the measurements to yards.

There are 3 feet in a yard and 12 inches in a foot. Hence

20 feet is 20/3 yards


3 inches is 3/12 feet which is 3/(123) yards.

In a similar fashion convert all the measurements to yards and then find the volume of each of the two slabs in cubic yards.