ASVAB (Armed Services Vocational Aptitude Battery)Mathematics Knowledge (MK)Medium
A construction crew is pouring concrete. If 3 workers can pour a foundation in 8 hours, how many hours will it take 4 workers to pour the same foundation, assuming they work at the same rate?
- A10.67 hours
- B5 hours
- C6 hours
- D7 hours
Show answer & explanationAnswer & explanation
Correct answer: C. 6 hours
This is an inverse proportion problem. The total 'work units' are 3 workers * 8 hours = 24 worker-hours. With 4 workers, it will take 24 worker-hours / 4 workers = 6 hours.
Why the other options are wrong
- A. This would be the time if there were fewer workers (e.g., 2 workers).
- B. This is an incorrect calculation, possibly 8 - 3.
- D. This is an incorrect calculation, possibly 8 - 1.
Inverse Proportion
A relationship where an increase in one quantity results in a proportional decrease in another, such that their product remains constant.
- Quantity1 × Quantity2 = Constant.
- Often involves workers and time, or speed and time.
- If workers increase, time decreases.
Memory trick: Proportions are Parallel Paths to Progress.