GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 08 Apr 2020, 11:50

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Pipe A fills a tank of capacity 700 liters at the rate of 40

Author Message
TAGS:

### Hide Tags

Intern
Joined: 30 Apr 2016
Posts: 39
Location: India
Concentration: Entrepreneurship, General Management
Schools: Stern '19 (S)
GMAT 1: 640 Q44 V35
GMAT 2: 700 Q49 V37
GPA: 3.8
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

01 Nov 2016, 05:32
What an amazing sum!

1 min work of Pipe A : 40 l.
1 min work of Pipe B : 30 l.
1 min work of Pipe C : -20 l.

3 min work : 50 l.

Notice how this is a cycle and not '1' unit of time work.

Thus, 13 'cycles' would make = 13*50l = 650l.
Now, Pipe A + Pipe B 1 minute work would fill in 70 litres.

Thus, 720 litres are filled (Hence it has to be under 41 minutes)
Thus, Answer : 40 minutes 20 seconds.
Current Student
Joined: 20 Jan 2017
Posts: 50
Location: United States (NY)
Schools: CBS '20 (A)
GMAT 1: 750 Q48 V44
GMAT 2: 610 Q34 V41
GPA: 3.92
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

03 Feb 2017, 06:02
1) 1:+40; 2:+30; 3:-20... 50l/3min
2) 650/50=13; 13*3=39min
3) last round: 650+40(1minute)+10(1/3 of a minute)
4) 39+1+1/3=40 minutes 20 seconds

Posted from my mobile device
Retired Moderator
Status: The best is yet to come.....
Joined: 10 Mar 2013
Posts: 478
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

31 Mar 2017, 23:21
Bunuel wrote:
aiming4mba wrote:
Pipe A fills a tank of capacity 700 liters at the rate of 40 liters a minute. Another pipe B fills the same tank at the rate of 30 liters a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 liters a minute. If pipe A is kept open for a minute and then closed and pipe B is open for a minute and then closed and then pipe C is open for a minute and then closed and the cycle is repeated, when will the tank be full?

In three minutes net gain is 40+30-20=50 liters;

After 13 cycles (13*3=39 minutes) net gain will be 13*50=650 liters.

Then in 1 minute pipe A will add 40 liters, 10 liters to be filled;

Then to fill 10 liters pipe B will need 10/30=1/3 min.

So total time $$39+1+\frac{1}{3}=40\frac{1}{3}$$ min.

Why this process is not working for below?

https://gmatclub.com/forum/pipe-a-and-p ... 80611.html

Pipe A and Pipe B fill water into a tank of capacity 1000 litres at the rate of 100 litres/minute and 25 litres/minute respectively. Pipe C drains water from the same tank at the rate of 50litres/minute. Pipe A is kept open for a minute and then closed, then pipe B is kept open for a minute and then closed, followed by a drain pipe C for a minute and then closed. This process is repeated until the tank is full. How long will it take to fill the tank.

A) 39 mins
B) 40 mins
C) 39 mins and 20 secs
D) 37 mins
E) 41 mins

In three minutes net gain is 100+25-50=75 liters;

After 13 cycles (13*3=39 minutes) net gain will be 13*75=975 liters.

Then to fill 25 liters pipe A will need 25/100=1/4 min.

So total time $$39+\frac{1}{4}$$ min = 39 min 15 sec

_________________
Hasan Mahmud
Director
Joined: 17 Dec 2012
Posts: 619
Location: India
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

06 Jun 2017, 15:23
aiming4mba wrote:
Pipe A fills a tank of capacity 700 liters at the rate of 40 liters a minute. Another pipe B fills the same tank at the rate of 30 liters a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 liters a minute. If pipe A is kept open for a minute and then closed and pipe B is open for a minute and then closed and then pipe C is open for a minute and then closed and the cycle is repeated, when will the tank be full?

A) 42 minutes
B) 14 minutes
C) 39 minutes
D) 40 minutes 20 seconds
E) None of these

1. In a cycle of 3 minutes, 40+30-20=50 liters are filled
2. In 13 such cycles, 13*50 = 650 liters are filled.
3. Then in the next fresh cycle, A fills 40 liters and 690 liters are filled.
4. The remaining 10 liters are filled by B in 20 seconds for a total time of 40 minutes 20 seconds
_________________
Srinivasan Vaidyaraman
Magical Logicians

Holistic and Holy Approach
Director
Joined: 20 Feb 2015
Posts: 722
Concentration: Strategy, General Management
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

03 Jul 2018, 04:38
aiming4mba wrote:
Pipe A fills a tank of capacity 700 liters at the rate of 40 liters a minute. Another pipe B fills the same tank at the rate of 30 liters a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 liters a minute. If pipe A is kept open for a minute and then closed and pipe B is open for a minute and then closed and then pipe C is open for a minute and then closed and the cycle is repeated, when will the tank be full?

A) 42 minutes
B) 14 minutes
C) 39 minutes
D) 40 minutes 20 seconds
E) None of these

A = + 40 litres a minutes
B= + 30 litres a minute
C=-20 litres a minute

total transaction in 3 minutes
40+30-20=50 litres

600 litres in 6*6 = 36 minutes
670 litres in 38 minutes
650 litres in 39 minutes
690 in 40 minutes
need 10 more litres which is 1/3rd the rate of B
so 60/3=20 seconds
D
Manager
Joined: 25 Apr 2016
Posts: 59
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

03 Jul 2018, 09:41
Bunuel wrote:
aiming4mba wrote:
Pipe A fills a tank of capacity 700 liters at the rate of 40 liters a minute. Another pipe B fills the same tank at the rate of 30 liters a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 liters a minute. If pipe A is kept open for a minute and then closed and pipe B is open for a minute and then closed and then pipe C is open for a minute and then closed and the cycle is repeated, when will the tank be full?

In three minutes net gain is 40+30-20=50 liters;

After 13 cycles (13*3=39 minutes) net gain will be 13*50=650 liters.

Then in 1 minute pipe A will add 40 liters, 10 liters to be filled;

Then to fill 10 liters pipe B will need 10/30=1/3 min.

So total time $$39+1+\frac{1}{3}=40\frac{1}{3}$$ min.

can't we instead first figure out first 630 litres of the tank's capacity would get obtained in what time and add 2 more minutes to it ?
Intern
Joined: 30 Jun 2018
Posts: 2
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

04 Jul 2018, 19:44
Bunuel wrote:
aiming4mba wrote:
Pipe A fills a tank of capacity 700 liters at the rate of 40 liters a minute. Another pipe B fills the same tank at the rate of 30 liters a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 liters a minute. If pipe A is kept open for a minute and then closed and pipe B is open for a minute and then closed and then pipe C is open for a minute and then closed and the cycle is repeated, when will the tank be full?

In three minutes net gain is 40+30-20=50 liters;

After 13 cycles (13*3=39 minutes) net gain will be 13*50=650 liters.

Then in 1 minute pipe A will add 40 liters, 10 liters to be filled;

Then to fill 10 liters pipe B will need 10/30=1/3 min.

So total time $$39+1+\frac{1}{3}=40\frac{1}{3}$$ min.

Question: It takes 3 mins (or 1 cycle by A, B, C) to fill 50 liters. How many mins to fill 700 liters (say x)? x = 700 x 3 / 50 = 42 mins?
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 6030
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40  [#permalink]

### Show Tags

24 Sep 2019, 01:24
net flow rate ; 40+30-20 ; 50 ltrs every 3 mins
700 ltrs nearest round value ; 650 ltrs ; in 13*3 ; 39 mins
in 1 min additional ; 40 ltrs from pipe A ; 690 ltrs
and Pipe B ; 10/30 ; 1/3 mins
or say 40 mins * 1/3 * 60 ; 40 mins and 20 sec
IMO D

aiming4mba wrote:
Pipe A fills a tank of capacity 700 liters at the rate of 40 liters a minute. Another pipe B fills the same tank at the rate of 30 liters a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 liters a minute. If pipe A is kept open for a minute and then closed and pipe B is open for a minute and then closed and then pipe C is open for a minute and then closed and the cycle is repeated, when will the tank be full?

A) 42 minutes
B) 14 minutes
C) 39 minutes
D) 40 minutes 20 seconds
E) None of these
Re: Pipe A fills a tank of capacity 700 liters at the rate of 40   [#permalink] 24 Sep 2019, 01:24

Go to page   Previous    1   2   [ 28 posts ]

Display posts from previous: Sort by