A vibratory roller has a width of 2 meters and a speed of 4 km/h. If the compaction efficiency is 80% and the overlap between passes is 10%, then how many square meters can the roller compact in 5 hours?
- A25,600 m²
- B32,000 m²
- C36,000 m²
- D28,800 m²Correct
Solution
Concept
Area compacted per hour
Formula
Area = effective width × speed × efficiency × time
Step-by-step solution
1. Effective width = 2 × (1 − 0.10) = 1.8 m. 2. Area per hour = 1.8 × 4000 × 0.8 = 5760 m². 3. In 5 hours = 28 800 m².
Explanation
Overlap reduces the effective width, and efficiency reduces the output.
Why the other options are wrong
25 600, 32 000 and 36 000 do not allow for both the overlap and efficiency.
Shortcut
Width × speed × eff × time.
Common mistake
Using the full width.
Correct answer: D) 28,800 m²