Multiple choice

A pipe can empty a tank in 30 hours. A second pipe can empty it in 45 hours. If both the pipes operate simultaneously, how much time is needed to empty the tank?

  1. 30 hours

  2. 18 hours

  3. 14 hours

  4. 15 hours
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Combined rate = 1/30 + 1/45 = (3+2)/90 = 5/90 = 1/18 tank per hour. Time = 18 hours to empty the tank. This is a standard pipes problem where rates add when working together.

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