If 6 equally productive workers finish a task in 12 days, how many worker-days does it require?

Question: If 6 equally productive workers finish a task in 12 days, how many worker-days does it require?

1. 72 worker-days
2. 73 worker-days
3. 71 worker-days
4. 74 worker-days

Correct Answer: A — 72 worker-days

Explanation: Worker-days = number of equal-rate workers × days worked.
Using the values in this question gives 72 worker-days as the correct answer.