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Working at a constant rate and by himself, it takes worker U three hou

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V
Joined: 02 Sep 2009
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Kudos [?]: 135392 [0], given: 12691

Working at a constant rate and by himself, it takes worker U three hou [#permalink]

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New post 16 Oct 2017, 00:45
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A
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D
E

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  15% (low)

Question Stats:

86% (00:51) correct 14% (00:46) wrong based on 65 sessions

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Working at a constant rate and by himself, it takes worker U three hours to fill up a ditch with sand. How long would it take for worker V to fill up the same ditch working by herself?

(1) Working together but at the same time U and V an fill in the ditch in 1 hour 105/2 minutes.
(2) In any length of time worker V fills in only 60% as much as worker U does in the same time.
[Reveal] Spoiler: OA

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Kudos [?]: 135392 [0], given: 12691

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S
Joined: 17 Oct 2016
Posts: 148

Kudos [?]: 38 [0], given: 89

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Re: Working at a constant rate and by himself, it takes worker U three hou [#permalink]

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New post 16 Oct 2017, 01:12
option D

From Q stem U takes 3 hours. we need to find V's time to work.

st1 say the combined working rate as 1 hour 105/2 minutes=112.5 minutes

clearly we can find the rate of individual work from the combined work.

1/U + 1/V = 1/112.5

=> 1/V = 1/300

therefore V take 5 hours= 300 minutes

st2 says U's time = 60%of V's time. directly gives the answer
U = 0.6 V
V=180/0.6
V= 300 minutes or 5 hours

Hence D
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Kudos [?]: 38 [0], given: 89

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Re: Working at a constant rate and by himself, it takes worker U three hou [#permalink]

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New post 22 Oct 2017, 14:34
I am going with D.
ST)If it takes the first worker 180 mins to finish the job and it takes both of the 105/2=52.5 minutes. We can use (xy/x+y) formula to get an answer. 1 is sufficient.
ST2) V=U/.6, U=3, so it takes V, 5 hours, from there we can use the formula from above to get 15/8 as the amount of time it takes them together.
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Kudos [?]: 8 [0], given: 18

Re: Working at a constant rate and by himself, it takes worker U three hou   [#permalink] 22 Oct 2017, 14:34
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Working at a constant rate and by himself, it takes worker U three hou

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