Working with Units

Question

A new sidewalk will be 6feet wide,120 feet long, and filled to a depth of 6 inches (0.5 foot) with concrete. How many cubic yards of concrete are needed?

The new sidewalk needs _________cubic yards of concrete.

 

(Round to one decimal place as needed.)

Answer 1

to approach this question you must understand that you are solving for the volume of a rectangular structure with the following dimensions given in feet  L x W x H: 120 x 6 x 0.5 = 360 feet³ or 360 cubic feet.

 

The second step is to convert the units to yards.

360 ft³ x 1yd³  = 13.3 yd³

              27ft³

 

or you can individually convert each dimension from feet to yard then multiply them all to get the cubic yards of concrete needed. An example for one of the dimensions is shown below.

 

120ft x 1yd = 40yd

            3ft

Answer 2

V=l*w*h

V=120*6*0.5

V=120*3

V=360 cubic feet

1 cubic yard equals 3*3*3=27 cubic feet

360/27=13.333... cubic yards

rounded: 13.3 cubic yards