Rate

[undvaulter]

A certain liquid passes through a drain at a rate of w/20 gallons every x seconds. At that rate, how many minutes will it take y gallons to pass through the drain?

y/1200xy

20xy/w

xy/3w

w/3xy

3y/wx

[ps63739]

In one second w/(20*x) Gallons will pass or the rate is w/(20*x) gallons/second.
So y/(w/20x) = Number of seconds.
20xy/w = total number of seconds. For minutes devide by 3600,

xy/1200w?

[thoppae.saravanan]

20xy/w = total number of seconds. For minutes devide by 3600

From seconds to hours you need to divide by 3600. For this problem we need to convert seconds to minutes hence we have to divide the value by 60 => 20xy/60w = xy/3w.

Option C should be the right answer.

[undvaulter]

Im not understanding how you arrived at w/(20*x)
The question states "at a rate of w/20 gallons every x seconds"
Doesnt this mean the rate is w/20 and the time is x, thus the set up should be (w/20)*x, or rate*time (gallons*seconds)

[ps63739]

Thanks thoppae.saravanan. I was taking in hours, sorry my mistake.

undvaulter,

In x seconds w/20 gallons,
so in 1 second w/(20*x) gallons.

In simple terms, suppose you can count till 120 in 30 seconds
So in 1 second, till how much can you count?

Assume x = 30. 120 = w/20. Makes sense?

[undvaulter]

Thank you for the reply, but im still a bit confused.

In the simple example provided above, 30seconds is the time, 120 is the distance, thus 4 would be the rate. R*T=D

This may be where my confusion lies. You stated the 120 is the w/20, however the 120(what you can count til) is the distance and the w/20 is the rate ("at a rate of w/20 gallons.")

The Rate in the original equation is w/20
The Time is x
so (w/20) * x or (w/20) * (x/1)
thus wx/20
this will give you an answer in seconds, so to convert that into minutes you get
wx/20=y/60

my final answer is 3wx/y

[douglas_longo]

it's easiest to pick numbers for each letter, plug them in and get a target number.
w=10
x=6
y=6

10/20= 1/2 gallon every 6 seconds = 6 gallons in 72 seconds

convert to minutes 72/60 = 6/5

now plug in the numbers you picked into each answer until one yields 6/5

C) 6(6)/3(10) 36/30 = 6/5

[Ben Ku]

Please cite the source (author) of this problem. We cannot reply unless a source is cited (and, if no source is cited, we will have to delete the post!). Thanks.

[akhan]

The source of this question is Princeton Review, Online Test (1). (Comes via purchase of their PR GMAT book) The question, in its entirety is as follows:

A certain liquid passes through a drain at a rate of gallons every x
seconds. At that rate, how many minutes will it take y gallons to pass through the drain?

a) y/200xy
b) 20xy/w
c) xy/3w
d) w/3xy
e) 3y/wx

I chose "C" as the OA.

[jnelson0612]

I concur with the poster who suggested choosing and plugging in real numbers. This problem is quite simple once that is done.