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Together,two pipes can fill  a reservoir in 3/4 of an hour.Pipe1 needs one hour ten minutes(1 1/6 hours)to fill the reservoir by itself.How long would pipe 2 need to fill the reservoir by itself?

 May 21, 2020
 #1
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Hard question. Wait until grandpa wakes up! @CPhill, @Melody, @Alan, @hugo aka sir grapes, and @Omi67 the sheep, u gotta solve this for our precious guest. laugh

 
 May 21, 2020
 #2
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Let r1 = fill rate of pipe 1, r2 = fill rate of pipe 2, V = reservoir volume.

 

r1 = V/(7/6)  = 6V/7   (1)

 

r2 = V/t        (2)        t = time for pipe 2 to fill reservoir by itself

 

r1 + r2 = V/(3/4) = 4V/3     (3)

 

Use (1) in (3)

 

6V/7 + r2 = 4V/3    so   r2 = 10V/21   (4)

 

Use (4) in (2)

 

10V/21 = V/t    t = 21/10   t = 2hrs 6mins

 
 May 21, 2020

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