Pipe A fills a tank in 10 hours and pipe B fills the same tank in 15 hours. How long will they take to fill the tank together?
Answer and explanation
Correct answer: D. 6 hours
- Step 1: In one hour A fills 1/10 of the tank and B fills 1/15.
- Step 2: Together 1/10 + 1/15 = 25/150 per hour, so the time is 150/25 = 6 hours.
Answer
6 hours.
Why not the others: 12,5 hours: the times were averaged. 25 hours: the times were added. 5 hours: the times were subtracted.
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