GED Mathematical Reasoning TestQuantitative Problem Solving with MeasurementMedium
A painter is hired to paint the walls of a cylindrical water tower. The tower has a radius of 7 feet and a height of 20 feet. If a single can of paint covers 300 square feet, how many cans of paint will the painter need to buy to cover the entire lateral surface of the tower?
- A3 cans
- B4 cans
- C5 cans
- D2 cans
Show answer & explanationAnswer & explanation
Correct answer: A. 3 cans
First, calculate the lateral surface area of the cylinder using the formula 2πrh. Then, divide the total area by the coverage per can to find the number of cans needed. Round up to the next whole number since you can't buy a fraction of a can.
Why the other options are wrong
- B. This option results from an overestimation or calculation error.
- C. This option suggests a significant overestimation of paint needed.
- D. This option results from incorrect calculation or rounding down.
Lateral Surface Area of a Cylinder
The area of the curved side of a cylinder, excluding the top and bottom circular bases.
- Formula: 2πrh
- Used for painting, wrapping, or covering the side of cylindrical objects
- Units are typically square units (e.g., ft², m²)
Memory trick: Radius Height Paint