Multiple choice

Two pipe A and B can fill tank in 45 minutes. If pipe A can fill a empty tank in 1 hour, how long will it take pipe B to fill the tank?

  1. 2 hours

  2. 3 hours

  3. 1 hours

  4. 4 hours
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Combined rate: 1/45 tank per minute. Pipe A rate: 1/60 tank per minute. Pipe B rate = combined - A = 1/45 - 1/60 = (4-3)/180 = 1/180. So Pipe B takes 180 minutes = 3 hours to fill alone.

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