Question 887483
a pump can empty a small pond in 5hr. another more efficient pump can do the job in 3hr. how long would it take to empty the pond if both pumps were used?
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The 1st pump does 1/5 of the pond per hour.
The 2nd pump does 1/3 of the pond per hour.
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Together, they do 1/5 + 1/3 of the pond per hour, = 8/15 of the pond/hour.
--> 15/8 hours/pond