One worker finishes a job in 10 days and another worker finishes it in 20 days. How long will they take if they work together?
Answer and explanation
Correct answer: D. 20/3 days
- Step 1: Their daily rates are 1/10 and 1/20, which add up to 30/200, so the time is 200/30 = 20/3 days. Answer: 20/3 days. Why not the others: 15 days: averages the two times. 30 days: adds the two times. 10 days: subtracts the times.
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