If a pipe can fill a tank in 9 hours and another pipe can fill it in 6 hours, ho

Practice Questions

Q1
If a pipe can fill a tank in 9 hours and another pipe can fill it in 6 hours, how long will it take to fill the tank if both pipes are opened together?
  1. 3.6 hours
  2. 4 hours
  3. 4.5 hours
  4. 5 hours

Questions & Step-by-Step Solutions

If a pipe can fill a tank in 9 hours and another pipe can fill it in 6 hours, how long will it take to fill the tank if both pipes are opened together?
Correct Answer: 3.6 hours
  • Step 1: Determine the rate at which each pipe fills the tank. The first pipe fills the tank in 9 hours, so its rate is 1/9 of the tank per hour.
  • Step 2: The second pipe fills the tank in 6 hours, so its rate is 1/6 of the tank per hour.
  • Step 3: Add the rates of both pipes together to find the combined rate. This is 1/9 + 1/6.
  • Step 4: To add 1/9 and 1/6, find a common denominator. The least common multiple of 9 and 6 is 18.
  • Step 5: Convert 1/9 to 2/18 and 1/6 to 3/18.
  • Step 6: Now add the two fractions: 2/18 + 3/18 = 5/18.
  • Step 7: The combined rate of both pipes is 5/18 of the tank per hour.
  • Step 8: To find out how long it takes to fill the entire tank, take the reciprocal of the combined rate: 1 / (5/18) = 18/5 hours.
  • Step 9: Simplify 18/5 to get 3.6 hours.
  • Rate of Work – Understanding how to calculate the combined work rate of multiple entities working together.
  • Fraction Addition – Adding fractions with different denominators to find a common rate.
  • Time Calculation – Converting the combined rate into time taken to complete a task.
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