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Make a table and solve. Round to the nearest tenth of necessary
It takes 9 hr for one water pipe to fill a swimming pool. If another pipe is added and both pipes work together,
the pool fills in only 3 hr. How long would it take the second pipe to fill the pool if it were the only one used?
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"It takes 9 hr for one water pipe to fill a swimming pool."
It means that the first pipe fills of the swimming pool volume per hour.
When both pipes work together, they fill {{1/3}}} of the swimming pool volume per hour.
Hence, the second pipe fills only = = of the swimming pool volume per hour, if it works alone.
It means that it takes = 4.5 hours for the second pipe to fill the tank if it works alone.
Answer. 4.5 hours.
There is a variety of similar problems on joint work in this site with detailed solutions and explanations.
Read these lessons, and you will learn on how to solve these problems once and for all.
Read them, consider them as samples, and get trained in solving these problems.
- Rate of work problems,
- Using Fractions to solve word problems on joint work,
- Solving more complicated word problems on joint work,
- Selected joint-work word problems from the archive
- Joint-work problems for 3 participants.
I never use tables for solving these and other problems.
I believe that the logic and understanding work much better than tables.