Helicopter Landing Pad – Area and Cost of Paint
publish date: 2026/05/17 19:43:28.266030 UTC
Orange paint is available in gallon containers at $19 each, and each gallon covers 375 ft². A circular helicopter landing pad has a diameter of 60 feet. How much will it cost to paint the pad?
How many gallons of paint must be purchased, and what is the total cost?
Correct Answer
Explanation
Step 1 — Find the area of the pad.
The diameter is 60 feet, so the radius is \(r = 30\) ft.
\[A = \pi r^2 = \pi(30)^2 = 30^2\pi = 900\pi \text{ ft}^2\]
Substitute one-half of 60 for \(r\). Write with \(\pi\) as the last factor. The area is exactly \(900\pi\) ft².
Step 2 — Find the number of gallons needed.
Since each gallon covers 375 ft², divide the area by 375:
\[\text{Gallons} = \frac{900\pi}{375} \approx 7.54\]
Because paint comes only in full gallons, the painter must purchase 8 gallons.
Step 3 — Find the cost.
\[\text{Cost} = 8 \times \$19 = \$152\]
Reference
Mathematics for college students