Answer:
18 ft³
Step-by-step explanation:
Consider the given figure showing the steps to consists of 3 rectangle prism or cuboid.
The cubic feet of concrete necessary = sum of the volume of the 3 cuboid/rectangular prism
Volume = l*w*h
Dimension of each cuboid:
Note that 1 ft = 12 inches
First cuboid:
Length (l) = 48 in = 48/12 = 4 ft
Width (w) = 36 in = 36/12 = 3 ft
Height (h) = 9 in = 9/12 = 0.75 ft
Volume = 4*3*0.75 = 9 ft³
Second cuboid:
Length (l) = 48 in = 48/12 = 4 ft
Width (w) = 24 in = 24/12 = 2 ft
Height (h) = 9 in = 9/12 = 0.75 ft
Volume = 4*2*0.75 = 6 ft³
Third cuboid:
Length (l) = 48 in = 48/12 = 4 ft
Width (w) = 12 in = 12/12 = 1 ft
Height (h) = 9 in = 9/12 = 0.75 ft
Volume = 4*1*0.75 = 3 ft³
Cubic feet of concrete necessary for the steps = 9 + 6 + 3 = 18 ft³
