SOLUTION: One pipe can fill a pool in 8 hours. The drain can empty it in 14 hours. With the pipe on and the drain open, how long will it take the pool to be filled?
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Question 252637: One pipe can fill a pool in 8 hours. The drain can empty it in 14 hours. With the pipe on and the drain open, how long will it take the pool to be filled? Found 2 solutions by drk, ankor@dixie-net.com:Answer by drk(1908) (Show Source):
You can put this solution on YOUR website! This is job / time. Here is the formula:
J1 / T1 * (together time) + J2 / T2 * (together time) = total number of jobs.
One pipe can do 1 job in time of 8 hours. So,
J1/T1 = 1/8.
Drain can empty 1 pool in 14 hours. So,
J2/T2 = 1/14.
They are actually working against each other - one fill and one drain.
The total number of jobs is 1. SO, we get
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step 1 - multiply both sides by LCD = 56
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step 2 -solve for t.
t ~ 56/3 hours
You can put this solution on YOUR website! One pipe can fill a pool in 8 hours.
The drain can empty it in 14 hours.
With the pipe on and the drain open, how long will it take the pool to be filled?
:
Let t = time to fill the pool under these conditions
Let the completed job = 1 (a full pool)
:
minus means drain
: - = 1
multiply equation by 56, results
7t - 4t = 56
3t = 56
t =
t = 18 hrs, or 18 hrs 40 min
:
:
Check solution
18.67/8 - 18.67/14 =
2.33 - 1.33 = 1
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