Question

a new sidewalk will be 5 feet wide, 140 feet long, and filled to a depth of 3 inches (0.25 foot) with concrete. how many cubic yards of concrete are needed? the new sidewalk needs 0.15 cubic yards of concrete (round to one decimal place as needed )

Explanation:

Step1: Calculate volume in cubic - feet

The volume $V$ of a rectangular - prism (which the sidewalk is) is given by $V = l\times w\times h$, where $l = 140$ feet, $w = 5$ feet, and $h=0.25$ feet.
$V=140\times5\times0.25=\frac{140\times5}{4}=175$ cubic feet.

Step2: Convert cubic - feet to cubic - yards

Since 1 yard = 3 feet, 1 cubic yard = $3\times3\times3 = 27$ cubic feet.
Let $x$ be the volume in cubic yards. Then $x=\frac{175}{27}\approx6.5$ cubic yards.

Answer:

$6.5$