Question
- A water tank can be filled with water by two pipes
in 1 hour and 20 minutes. If the smaller pipe takes
2 hours longer than the larger pipe to fill the tank,
find the time taken by each pipe to fill the tank.
in 1 hour and 20 minutes. If the smaller pipe takes
2 hours longer than the larger pipe to fill the tank,
find the time taken by each pipe to fill the tank.
Ask by Whittaker Bright. in Singapore
Mar 21,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
The larger pipe takes 2 hours to fill the tank, and the smaller pipe takes 4 hours to fill the tank.
Solution

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Bonus Knowledge
To solve this problem, let’s denote the time taken by the larger pipe to fill the tank as
hours. This means the smaller pipe takes
hours.
The work done by both pipes in one hour is:
- The larger pipe does
of the tank in one hour. - The smaller pipe does
of the tank in one hour.
Together, they can fill the tank in
hour and
minutes, which is
hours. Therefore, their combined rate of work is:
Now, clearing the fractions gives:
Simplifying leads to:
Multiplying through by
to eliminate the fraction:
Rearranging:
Now, we can solve this quadratic equation using the quadratic formula where
:
This gives us two possible solutions:
-
hours (larger pipe) -
hours (not valid since time cannot be negative)
Thus, the larger pipe takes
hours to fill the tank, and the smaller pipe, which takes
hours longer, takes
hours.
So, the larger pipe fills the tank in
hours, while the smaller pipe fills it in
hours.