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An empty pool being filled with water at a constant rate [#permalink]
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20 Dec 2012, 05:53
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An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool? (A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min
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Re: An empty pool being filled with water at a constant rate [#permalink]
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20 Dec 2012, 05:56
Walkabout wrote: An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?
(A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min As pool is filled to 3/5 of its capacity then 2/5 of its capacity is left to fill. Since it takes 8 hours to fill 3/5 of the pool, then to fill 2/5 of the pool it will take 8/(3/5)*2/5 = 16/3 hours = 5 hours 20 minutes (because if t is the time needed to fill the pool then t*3/5=8 > t=8*5/3 hours > to fill 2/5 of the pool 8*5/3*2/5=16/3 hours will be needed). Or plug values: take the capacity of the pool to be 5 liters > 3/5 of the pool or 3 liters is filled in 8 hours, which gives the rate of 3/8 liters per hour > remaining 2 liters will require: time = job/rate = 2/(3/8) = 16/3 hours = 5 hours 20 minutes. Answer: B.
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Re: An empty pool being filled with water at a constant rate [#permalink]
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26 Jan 2013, 05:33
I tried using just ratios to solve this (because rate is constant):
8Hrs to fill 3/5 tank i.e 0.6 of the tank X hrs to fill 2/5 tank i.e 0.4 of the tank
=> 8/0.6 = X/0.4 => X=3.2/0.6 = 32/6 = 16/3 = 5.33hrs i.e 5hr20min



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Re: An empty pool being filled with water at a constant rate [#permalink]
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28 Jan 2013, 14:28
Hey, Is'nt 16/3 = 5.3 ~ . This might be silly, but i chose 5 hours 30 mins . I don't want to make this mistake again, kindly help me Thanks Aj



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Re: An empty pool being filled with water at a constant rate [#permalink]
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28 Jan 2013, 15:11
30 minutes/60 minutes=.5, so 5 and a half hours would be 5.5, not 5.33.



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Re: An empty pool being filled with water at a constant rate [#permalink]
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21 May 2015, 04:55
Let the total amount of water eq l
then rate : ( 3/5 * l ) / 8 = 3/40 * l
So time required to fill the full tank = l / ( (3/40) * l ) = 40/3
So time required to fill the remaining section = ( 40/3  8 ) hrs = 16/3 hrs = 5 1/3 hrs = 5 hr 20 min



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Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink]
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29 May 2015, 21:03
As per what I did, 8 Hours  3/5 of capacity ? Time  to fill remaining  2/5 of capacity. But the answer I am getting is incorrect. Could someone share the appropriate process to work on this?
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Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink]
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29 May 2015, 21:08
Hi Pretz, There are a couple of different ways to approach the math in this question. It looks like you started to set up a ratio, but didn't complete the work. Here's one way to go about it: Since it takes 8 hours to fill 3/5 of the pool and X hours to fill 2/5 of the pool..... 8/X = (3/5)/(2/5) Since both fractions are "over 5", we can multiply those 5s out (by multiplying the numerator and denominator by 5).... 8/X = 3/2 Now we can crossmultiply and solve for X.... 16 = 3X 16/3 = X 5 1/3 hours = X 5 1/3 hours = 5 hours 20 minutes Final Answer: GMAT assassins aren't born, they're made, Rich
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An empty pool being filled with water at a constant rate takes 8 hours [#permalink]
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29 May 2015, 21:46
Pretz wrote: As per what I did,
8 Hours  3/5 of capacity ? Time  to fill remaining  2/5 of capacity.
But the answer I am getting is incorrect. Could someone share the appropriate process to work on this? Hello there PretzI think your approach is fine. \(8\) \(hours\)  \(\frac{3}{5}\) multiply by \(\frac{5}{3}\) on both sides \(8*\frac{5}{3}\) \(hours\)  \(\frac{3}{5} *\frac{5}{3}\) \(\frac{40}{3}\) \(hours\)  \(1\) So it takes \(\frac{40}{3}\) \(hours\) to fill the tank The additional time required to fill \(\frac{2}{3}\)rd of the tank will be \(\frac{40}{3}  8\) \(hours\) \(\frac{16}{3}\) \(hours\) \(5 \frac{1}{3}\) \(hours\) \(5\) \(hours\) \(20\) \(minutes\) I hope that explains it
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Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink]
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29 May 2015, 21:53
If it takes 8 hours to fill 3/5 of the pool, then it takes 8/3 hours to fill 1/5 of the pool, and it thus takes 16/3 hours to fill 2/5 of the pool, which is what we need to do.
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Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink]
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29 May 2015, 22:05
Awesome! Thank you so much all!
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Re: An empty pool being filled with water at a constant rate [#permalink]
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01 Jun 2015, 02:53
B if the rates are constant the ratio of capacity is proportional to that of time x/8=2/3  x = 5 hr 20 min
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Re: An empty pool being filled with water at a constant rate [#permalink]
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02 Jun 2015, 09:13
An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?
(3/5) An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool? (3/5) of a pool/ 8 hours = 3/40 (the rate)
(3 pools/40 hours) = (2/5* pool)/ x hours Cross multiply 3x = (2/5) 40 3x = (2/5) (8) (5) 3x = 16 x = 16/3 or 5 1/3 1/3 of an hour = 20 minutes
* The pool is 3/5 full so 2/5 remains.
(A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min



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Re: An empty pool being filled with water at a constant rate [#permalink]
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17 May 2016, 05:59
We know, R * T = Q , suppose the Q=100ltr. then, R * 8 = 3/5 of 100 ==> 60/8 ==> 15/2 ltr per hour.
now, remaning 40ltr(which is 100  60 or 2/5 of 100) R * t = Q or, 15/2 * t = 40 or, t = 40 * 2/15 t = 16/3 = 5.33 = 5 hour + 1/3 and 1/3 of 60 = 20. so, 5 hour 20 mins.
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Re: An empty pool being filled with water at a constant rate [#permalink]
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17 May 2016, 17:01
Walkabout wrote: An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?
(A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min Solution: To solve we can setup a proportion. The proportion will read: A time of 8 hours is to filling up 3/5 of the pool is the same as a time of x number of hours is to filling up (the remaining) 2/5 of the pool. Setting this up mathematically we have: 8/(3/5) = x/(2/5) 8/(3/5) = x/(2/5) 40/3= 5x/2 Cross multiplying, we get: 80 = 15x 16 = 3x 16/3 = x 5 1/3 hours = x 5 hours and 20 minutes = x Answer: B
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Re: An empty pool being filled with water at a constant rate [#permalink]
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28 Oct 2017, 19:27
I don't see anyone converting 1/3 to minutes, this is why a lot of people are being confused with the answer. if you have 1/3 * 60 (minutes) then you get 20 minutes. Just wanted to clarify it for me. 5 + 1/3 = 5 + 20 minutes = 5 hrs and 20 minutes



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Re: An empty pool being filled with water at a constant rate [#permalink]
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08 Nov 2017, 22:03
An easier approach is to break up the math. \(\frac{16}{3}\) hrs = \(\frac{16}{3}*60\) mins = 16 * 20 mins = (10 + 6) * 20 = 200 + 120 = 300 + 20 = 5 hrs and 20 mins.
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Re: An empty pool being filled with water at a constant rate [#permalink]
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08 Nov 2017, 23:01
8 hours for 3/5 then 8/3 to fill 1/5 8/3*2 for to fill remaining 2/5 it equals to 5 hours 20 minutes
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Re: An empty pool being filled with water at a constant rate [#permalink]
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27 Feb 2018, 06:03
Walkabout wrote: An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?
(A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min life without work problems is not life, work problems are integral part of our daily life:) ok so here is solution We know formulas: work = rate * time Rate = \(\frac{work}{time}\) Time = \(\frac{work}{rate}\) Facts : it took 8 hours to complete \(\frac{3}{5}\) of work > Work done = 3/5 and Time = 8 and Rate = 3/5 / 8 = 3/40 Now we need to know how much TIME will it take to complete 2/5 of work > 2/5 / 3/40 = 16/3 so answer is 5 hours 30 minures



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Re: An empty pool being filled with water at a constant rate [#permalink]
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05 Mar 2018, 09:31
Walkabout wrote: An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?
(A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min Here's another approach: IMPORTANT CONCEPT: After 8 hours, 3/5 of the job is finished and 2/5 of the job is remaining. This means the remaining part of the job is 2/3 the size of the first part of the job. Think of it this way: If the pool had a capacity of 5 gallons, then the first part of the job would be filling 3 gallons, and the remaining part of the job is filling 2 gallons. So, the remaining part of the job (filling 2 gallons) is 2/3 the size of the first part of the job (filling 3 gallons) So, if it takes 8 hours to do the first part of the job, then the time to do the remaining part = 2/3 of 8 hours 2/3 of 8 hours = 2/3 x 8 hours = 16/3 hours = 5 1/3 hours = 5 hours 20 minutes Answer: B Cheers, Brent
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