Last visit was: 20 Jul 2025, 12:24 It is currently 20 Jul 2025, 12:24
Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
ksharma12
Joined: 03 Feb 2010
Last visit: 29 Apr 2012
Posts: 49
Own Kudos:
708
 [36]
Given Kudos: 4
Posts: 49
Kudos: 708
 [36]
4
Kudos
Add Kudos
32
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 20 Jul 2025
Posts: 102,633
Own Kudos:
Given Kudos: 98,235
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,633
Kudos: 743,058
 [15]
5
Kudos
Add Kudos
10
Bookmarks
Bookmark this Post
General Discussion
User avatar
YourDreamTheater
Joined: 22 Oct 2009
Last visit: 08 Sep 2012
Posts: 223
Own Kudos:
214
 [4]
Given Kudos: 1
GMAT 1: 760 Q49 V44
GPA: 3.88
GMAT 1: 760 Q49 V44
Posts: 223
Kudos: 214
 [4]
1
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
User avatar
ksharma12
Joined: 03 Feb 2010
Last visit: 29 Apr 2012
Posts: 49
Own Kudos:
708
 [1]
Given Kudos: 4
Posts: 49
Kudos: 708
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Yea i thought it was c too.

but its not.

This question is from the work/rate made easy thread in the beginning of the quant forum.


I figured knowing the rate per minute was not sufficient unless we knew the total.
User avatar
YourDreamTheater
Joined: 22 Oct 2009
Last visit: 08 Sep 2012
Posts: 223
Own Kudos:
214
 [1]
Given Kudos: 1
GMAT 1: 760 Q49 V44
GPA: 3.88
GMAT 1: 760 Q49 V44
Posts: 223
Kudos: 214
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I'm definitely agreeing with you here. Must be a typo -- or we're both missing something obvious!
avatar
ulm
Joined: 03 Jun 2010
Last visit: 20 Aug 2019
Posts: 95
Own Kudos:
600
 [2]
Given Kudos: 40
Location: United States (MI)
Concentration: Marketing, General Management
WE:Business Development (Consumer Packaged Goods)
Products:
Posts: 95
Kudos: 600
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
(1/A+1/B)*0.5=1
It means that the work is done by 2 employees.
From (1) we have A, so we can solve for B.
That's all.
(A)
avatar
smartmanav
Joined: 18 Jun 2012
Last visit: 23 Feb 2014
Posts: 27
Own Kudos:
22
 [1]
Given Kudos: 15
Posts: 27
Kudos: 22
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Can't we do this question using unitary method ?
User avatar
WoundedTiger
Joined: 25 Apr 2012
Last visit: 25 Sep 2024
Posts: 523
Own Kudos:
2,483
 [3]
Given Kudos: 740
Location: India
GPA: 3.21
WE:Business Development (Other)
Products:
Posts: 523
Kudos: 2,483
 [3]
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
smartmanav
Can't we do this question using unitary method ?


Hi Smartmanav,

I guess this cannot be done by Unitary method as we are given the Constant rate of A i.e 25L/min. Now does it tell you the time A will take alone to fill the tank. No, because we do not the volume/size of the tank.

That is why method suggested by Bunuel of Rate*Time =Work


Thanks
Mridul
avatar
madn800
Joined: 07 May 2013
Last visit: 11 Aug 2014
Posts: 67
Own Kudos:
65
 [1]
Given Kudos: 1
Posts: 67
Kudos: 65
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The standard formula for solving this problem is AB/A+B=1/2 hrs
we need A to get to B, where A is the time taken by Pipe A to fill ENTIRE tank alone
from options the time taken by Pipe A to fill ENTIRE tank alone=1200/25=48 minutes
substitute in equation above to get value of B. SIMPLE!
User avatar
elizaanne
Joined: 21 Apr 2014
Last visit: 30 Nov 2016
Posts: 32
Own Kudos:
90
 [3]
Posts: 32
Kudos: 90
 [3]
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
So let's put this into an equation. We know that (Arate+Brate)30min=T, if T= the tank's capacity.

(1) now we know that Arate=25lirer/min, so we can plug that into the equation and we get (25lit/min+Brate)30min=T

This is not sufficient, because there are still too many unkowns. For example, it T=900 liters then Brate would equal 5 liters/min. But if T=9,000 then Brate would equal 275 liters/min

(2) now we know that T= 1200 liters, plugging that into the equation we get (Arate+Brate)30min=1200 liters

This is also not sufficient, because there are a variety of different combinations of Arate and Brate that can fit this equation. For example, Arate could be 10 liters per min and Brate could be 30 liters per min OR vice versa.

Now lets try them both together by plugging (1) and (2) into the equation:

(25lit/min+Brate)30min=1200 liters

divide both sides by 30 min and we get: 25 liters/min+Brate=40liters/min

that means Brate equals 15 liters, so the answer is (C) both together are sufficient

In the actual GMAT, you would not need to go so far as to figure out exactly what B rate. That would be a waste of time. As soon as you know what you CAN solve it with both, which can be determined by the fact that there is only 1 unknown then you should select C and move on.
User avatar
LogicGuru1
Joined: 04 Jun 2016
Last visit: 28 May 2024
Posts: 469
Own Kudos:
2,537
 [1]
Given Kudos: 36
GMAT 1: 750 Q49 V43
GMAT 1: 750 Q49 V43
Posts: 469
Kudos: 2,537
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
ksharma12
Working together at their constant rates, A and B can fill an empty tank to capacity in 1/2 hours. What is the constant rate of pump B?

(1) A's constant rate is 25 LTS / min
(2) The tanks capacity is 1200 lts.
ksharma12
Working together at their constant rates, A and B can fill an empty tank to capacity in 1/2 hours. What is the constant rate of pump B?

(1) A's constant rate is 25 LTS / min
(2) The tanks capacity is 1200 lts.

Let the rate of A be a and the rate of B be b

(1) A's constant rate is 25 LTS / min
(a+b)time = Volume of tank
(25+b)*30 minutes = Volume of tank
750+30b = volume of tank
Rate of B and the volume of tank is not known
INSUFFICIENT

(2) The tanks capacity is 1200 lts.
(a+b)*time = 1200
(a+b)*30 minutes = 1200
30a+30b=1200
Rate of A and rate of B is not known
INSUFFICIENT

MERGE BOTH
750 + 30b= 30a+30b {since both equations are equal to 1200}
30a=750
a=750/30 = 25

Now rate of A is known. Rate of B can be easily calculated by putting value of in any equation
for example 30a+30b =1200
750+30b=1200
30b=450
b= 15

SUFFICIENT

ANSWER IS C

we need both statements together

ANSWER IS C
User avatar
arvind910619
Joined: 20 Dec 2015
Last visit: 18 Oct 2024
Posts: 850
Own Kudos:
601
 [1]
Given Kudos: 755
Status:Learning
Location: India
Concentration: Operations, Marketing
GMAT 1: 670 Q48 V36
GRE 1: Q157 V157
GPA: 3.4
WE:Engineering (Manufacturing)
Products:
GMAT 1: 670 Q48 V36
GRE 1: Q157 V157
Posts: 850
Kudos: 601
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Imo C
At first sight the answer seems to be statement 1 but on closer inspection we come to know about its flaw as the rate is given in 25 liters per minute and from the question stem we have been given only the completion time ,So we need the capacity of the tank .
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,463
Own Kudos:
Posts: 37,463
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102633 posts
455 posts