Question 71096
"3 Pipes of different sizes are filling up a pool. Pipe 1 fills it up a third of the time that it takes Pipe 3, and Pipe 2 fills it up a half of the time that it takes Pipe3. How long will it take each pipe to fill up the pool by itself?" 
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Let time for Pipe 3 be 6x hrs/job ; Rate = 1/6x job/hr
Pipe 2 time is 3x hrs/job ; Rate = 1/3x job/hr
Pipe 1 time is 2x hrs/job ; Rate = 1/2x job/hr
Time for all to fill = 3 hrs/job ; Rate = 1/3 job/hr

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EQUATION:
rate + rate + rate = rate together
1/6x + 1/3x + 1/2x = 1/3 
Multiply thru by 6x to get:
1 + 2 + 3 = 2x
x=3 hrs.
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Pipe 3 takes 6x or 18 hrs alone
Pipe 2 takes 3x or 9 hrs. alone
Pipe 1 takes 2x or 6 hrs. alone
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Cheers,
Stan H.