SOLUTION: One pipe alone will fill a tank in 7 1/2 hrs. A second pipe will fill it alone in 10 hrs. I the second pipe were open for 8 hrs. and then closed, how long would the first pipe take

Question 93298: One pipe alone will fill a tank in 7 1/2 hrs. A second pipe will fill it alone in 10 hrs. I the second pipe were open for 8 hrs. and then closed, how long would the first pipe take to finish filling the tank?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
One pipe alone will fill a tank in 7 1/2 hrs. A second pipe will fill it alone in 10 hrs. If the second pipe were open for 8 hrs. and then closed, how long would the first pipe take to finish filling the tank?
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1st pipe DATA:
Time = 15/2 hr/job ;Rate = 2/15 job/hr
--------------------
2nd pipe DATA:
Time = 10 hr/job ; Rate = 1/10 job/hr
----------------------
2nd for 8 hrs + 1st for x hrs = 1 job
8(1/10) + (2/15)x = 1
Multiply thru by 30 to get:
24 + 4x = 30
4x = 6
x= 3/2 hrs (time the 2nd pipe will take to finish the job)
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Cheers,
Stan H.

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