A tank can be filled by one pipe in 6 hours and by a second pipe in 4 hours. How long do both take to fill the empty tank together?
Answer and explanation
Correct answer: A. 2.4 hours
- Step 1: In 1 hour the pipes fill 1/6 + 1/4 = 5/12 of the tank. Step 2. Time = 12/5 = 2.4 hours. Answer: 2.4 hours. Why not the others: 5 hours: That averages the two times. 10 hours: That adds the two times. 24 hours: That multiplies the two times.
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