Question

Kevin plans to put concrete on a rectangular portion of his driveway. The portion is 10 feet long and 3 inches high. The price of concrete is $98 per cubic yard. The total cost of the concrete Keven needs is $72.59. Which of the following is closest to the width of the portion of the driveway on which Kevin plans to put concrete?
3 feet
6 feet
8 feet
10 feet

Answer 1

The answer is 8 feet

1 ft = 12 in
1 in = 0.083 ft

1 yd = 3 ft
1 yd³ = 27 ft³


We know:
l = 10 ft
h = 3 in = 3 * 0.083 ft = 0.25 ft
w = ?
The volume of a rectangular concrete is:
V = l * w * h
V = 10 ft * w * 0.25 ft
V = 2.5w ft²

The price is $98 per cubic yard:
$98/1yd³ = $98/27ft³ = $3.63/ft³

The price is $3.63 per cubic feet.
The total cost of the concrete Keven needs is $72.59:
V * $3.63 = $72.59
2.5w * 3.63 = 72.59
9.075w = 72.59
w = 72.59 / 9.075
w = 7.99 ≈ 8 ft