Pedro can paint a fence in 12 days and Rosa can paint it in 24 days. Working together at their usual rates, how many days do they need?
Answer and explanation
Correct answer: B. 8 days
- Step 1: Pedro's daily rate is 1/12 and Rosa's is 1/24.
- Step 2: Together 2/24 + 1/24 = 3/24 = 1/8 per day, so the job takes 8 days.
Answer
8 days.
Why not the others: Averaging or adding the times is not valid for combined work rates, and halving one time ignores Rosa's slower pace.
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