If 3 equally productive workers finish a task in 9 days, how many worker-days does it require?

Question: If 3 equally productive workers finish a task in 9 days, how many worker-days does it require?

1. 27 worker-days
2. 28 worker-days
3. 26 worker-days
4. 29 worker-days

Correct Answer: A — 27 worker-days

Explanation: Worker-days = number of equal-rate workers × days worked.
Using the values in this question gives 27 worker-days as the correct answer.