SOLUTION: Two inlet pipes can fill the pool with water in 3 hours and the other in 5 hours.An outlet pipe can empty the same pool in 6 hours.Given that the three pipes were open for 2 hours,

Algebra ->  Customizable Word Problem Solvers  -> Geometry -> SOLUTION: Two inlet pipes can fill the pool with water in 3 hours and the other in 5 hours.An outlet pipe can empty the same pool in 6 hours.Given that the three pipes were open for 2 hours,      Log On

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Question 1020437: Two inlet pipes can fill the pool with water in 3 hours and the other in 5 hours.An outlet pipe can empty the same pool in 6 hours.Given that the three pipes were open for 2 hours,what part of the work was done?pls help with a little explanation.Thanks in advance and more power....
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add rates of filling and subtract rates
of draining
Rate for 1st inlet pipe:
[ 1 pool filled ] / [ 3 hrs ]
Rate for 2nd inlet pipe:
[ 1 pool filled ] / [ 5 hrs ]
Rate for outlet pipe:
[ 1 pool drained ] / [ 6 hrs ] ( subtract this rate )
Rate for all 3 pipes open:
[ fraction of the pool filled ] / [ 2 hrs ]
--------------------------------
I can write the equation:
+1%2F3+%2B+1%2F5+-+1%2F6+=+x%2F2+
Multiply both sides by +30+
+10+%2B+6+-+5+=+15x+
+15x+=+11+
+x+=+11%2F15+
11/15 of the pool got filled in 2 hrs
-------------------------------
Note that in 3 hrs, the pool is overflowing, since
+1%2F3+%2B+1%2F5+-+1%2F6+=+x%2F3+
+10+%2B+6+-+5+=+10x+
+x+=+11%2F10+
( overflowed by +1%2F10+ )