One worker finishes a job in 10 days and another worker finishes it in 15 days. How long will they take if they work together?
Answer and explanation
Correct answer: B. 6 days
- Step 1: Their daily rates are 1/10 and 1/15, which add up to 25/150, so the time is 150/25 = 6 days. Answer: 6 days. Why not the others: 12.5 days: averages the two times. 25 days: adds the two times. 5 days: subtracts the times.
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