A tank can be filled by a pipe in 25 hours and emptied by another pipe in 50 hou

Practice Questions

Q1
A tank can be filled by a pipe in 25 hours and emptied by another pipe in 50 hours. If both pipes are opened together, how long will it take to fill the tank?
  1. 16.67 hours
  2. 20 hours
  3. 25 hours
  4. 30 hours

Questions & Step-by-Step Solutions

A tank can be filled by a pipe in 25 hours and emptied by another pipe in 50 hours. If both pipes are opened together, how long will it take to fill the tank?
Correct Answer: 50 hours
  • Step 1: Determine the filling rate of the first pipe. It fills the tank in 25 hours, so its rate is 1/25 of the tank per hour.
  • Step 2: Determine the emptying rate of the second pipe. It empties the tank in 50 hours, so its rate is 1/50 of the tank per hour.
  • Step 3: Calculate the net rate when both pipes are opened together. This is done by subtracting the emptying rate from the filling rate: (1/25) - (1/50).
  • Step 4: To subtract the fractions, find a common denominator. The common denominator for 25 and 50 is 50.
  • Step 5: Convert 1/25 to have a denominator of 50: (1/25) = (2/50).
  • Step 6: Now subtract: (2/50) - (1/50) = (1/50).
  • Step 7: The net rate of filling the tank is 1/50 of the tank per hour.
  • Step 8: To find out how long it takes to fill the entire tank, take the reciprocal of the net rate: 1 / (1/50) = 50 hours.
  • Rate of Work – Understanding how to calculate the rate at which a tank is filled or emptied by different pipes.
  • Combined Work Rate – Calculating the net effect of two pipes working together, one filling and one emptying.
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