Math in Water Pipes
Level
pending
One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?
The answer is 11.25.
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1 solution
Convert to rates: hours to complete job: fast pipe: f slow pipe: 1.25f together: 5
completed per hour: fast pipe: 1/f slow pipe: 1/1.25f together: 1/5
adding their labor:
1/f + 1/1.25f = 1/5
multiplying through by 5f:
5 + 5/1.25 = f 5 + 4 = f = 9
Then 1.25f = 11.25, so the slower pipe takes 11.25 hours.