Pipe A fills a tank in 6 hours and pipe B fills the same tank in 3 hours. How long will they take to fill the tank together?
Answer and explanation
Correct answer: B. 2 hours
- Step 1: In one hour A fills 1/6 of the tank and B fills 1/3.
- Step 2: Together 1/6 + 1/3 = 9/18 per hour, so the time is 18/9 = 2 hours.
Answer
2 hours.
Why not the others: 4,5 hours: the times were averaged. 9 hours: the times were added. 3 hours: the times were subtracted.
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