Multiple choice

If two pipes are opened simultaneously, they can fill an empty tank in 36 minutes. The first pipe, when operating alone, takes 90 minutes to fill the tank. If the second pipe releases 40 liters more water per minute than the first pipe, what is the total capacity of the tank?

  1. 2,700 liters

  2. 3,600 liters

  3. 6,300 liters

  4. 7,200 liters

  5. 8,100 liters
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipe 1 rate = 1/90. Combined rate = 1/36. Pipe 2 rate = 1/36 - 1/90 = (5-2)/180 = 3/180 = 1/60. Pipe 2 is faster by 1/60 - 1/90 = 1/180 per minute. 1/180 of capacity = 40 liters, so capacity = 40 * 180 = 7200.

AI explanation

Let the capacity of the tank be X liters, making the first pipe's rate X/90 liters per minute. Their combined rate is X/36, so the second pipe's rate is X/36 - X/90 = X/60 liters per minute. The problem states the second pipe releases 40 liters more per minute, giving the equation X/60 - X/90 = 40. Solving yields X/180 = 40, so X equals 7200 liters.

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