Last visit was: 02 Sep 2026, 11:59 It is currently 02 Sep 2026, 11:59
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
yrozenblum
Joined: 29 Mar 2020
Last visit: 20 Feb 2025
Posts: 27
Own Kudos:
2,335
 [270]
Given Kudos: 25
Posts: 27
Kudos: 2,335
 [270]
9
Kudos
Add Kudos
260
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 02 Sep 2026
Posts: 113,060
Own Kudos:
Given Kudos: 111,271
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 113,060
Kudos: 838,681
 [42]
24
Kudos
Add Kudos
18
Bookmarks
Bookmark this Post
User avatar
HarshavardhanR
Joined: 16 Mar 2023
Last visit: 02 Sep 2026
Posts: 649
Own Kudos:
755
 [28]
Given Kudos: 99
Status:Independent GMAT Tutor
Affiliations: Ex - Director, Subject Matter Expertise at e-GMAT
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 649
Kudos: 755
 [28]
21
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
General Discussion
User avatar
gmatophobia
User avatar
Quant Chat Moderator
Joined: 22 Dec 2016
Last visit: 30 Aug 2026
Posts: 3,174
Own Kudos:
12,304
 [13]
Given Kudos: 1,860
Location: India
Concentration: Strategy, Leadership
Posts: 3,174
Kudos: 12,304
 [13]
8
Kudos
Add Kudos
5
Bookmarks
Bookmark this Post
yrozenblum
Attachment:
Table.png

The chart above shows political and geographic data on a certain legislative committee of 20 members, each of whom belongs to 1 of 2 political parties and lives in 1 of 4 regions. How many subcommittees of this legislative committee are possible that contain exactly 1 member from each of the 4 regions and the same number of members from each of the 2 political parties?

A. 10
B. 20
C. 99
D.246
E. 495

A few points to note:

  • We need the same number of members from each of the 2 political parties. Hence, out of the four members, we need two members of party A and two members of party B.
  • We don't have any members of Party B in the West region. Hence, the member selected from the western region will belong to Party A.
  • So, we need to select only one member of party A who can be either from the North, South, or East region. Once, the region of the member from Party A is identified, the remaining two regions will have the member from Party B.
    For example, if the member from the north region belongs to Party A, then, the members from the remaining two regions i.e. South and East must belong to Party B

Hence, we can have the following combinations

  1. (West → Party A & North → Party A) (East → Party B & South → Party B)
  2. (West → Party A & South→ Party A) (East → Party B & North → Party B)
  3. (West → Party A & East → Party A) (North→ Party B & South → Party B)

Required combinations

  1. (West → Party A & North → Party A) (East → Party B & South → Party B) = \(^3C_1 * ^5C_1 * ^3C_1 * ^4C_1 = 180\)
  2. (West → Party A & South→ Party A) (East → Party B & North → Party B) = \(^3C_1 * ^1C_1 * ^3C_1 * ^2C_1 = 18\)
  3. (West → Party A & East → Party A) (North→ Party B & South → Party B) = \(^3C_1 * ^2C_1 * ^4C_1 * ^2C_1 = 48\)

Total possible combinations = 180 + 18 + 48 = 246

Option D
User avatar
DanTheGMATMan
Joined: 02 Oct 2015
Last visit: 01 Sep 2026
Posts: 385
Own Kudos:
277
 [10]
Given Kudos: 10
Expert
Expert reply
Posts: 385
Kudos: 277
 [10]
7
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
­Write out the possible combinations of regions for each party and then put the numbers in. Light work:

­
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 01 Sep 2026
Posts: 16,631
Own Kudos:
81,117
 [9]
Given Kudos: 489
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,631
Kudos: 81,117
 [9]
6
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
yrozenblum


The chart above shows political and geographic data on a certain legislative committee of 20 members, each of whom belongs to 1 of 2 political parties and lives in 1 of 4 regions. How many subcommittees of this legislative committee are possible that contain exactly 1 member from each of the 4 regions and the same number of members from each of the 2 political parties?

A. 10
B. 20
C. 99
D. 246
E. 495


Attachment:
The attachment 2023-12-05_20-53-06.png is no longer available
Attachment:
The attachment 2023-12-05_20-52-23.png is no longer available
­
A quick tree diagram will help here. They can be quite useful.
Note that West has only 3 Party A people (0 party B people)  so 1 of those must be selected. This gives us 3 ways.
Next, go to South - either 1 of Party A or 1 of the 4 party B can be selected. 

If party A is selected from South, then from north and east, party B candidates have to be selected and so on...

Attachment:
Screenshot 2024-06-22 at 4.37.43 PM.png
Screenshot 2024-06-22 at 4.37.43 PM.png [ 58.76 KiB | Viewed 24952 times ]

Total possible subcommittees = 18   + 48   + 180 = 246

Answer (D)
 ­
User avatar
SergejK
Joined: 22 Mar 2024
Last visit: 02 May 2025
Posts: 150
Own Kudos:
Given Kudos: 73
Posts: 150
Kudos: 1,110
Kudos
Add Kudos
Bookmarks
Bookmark this Post
As we have no overlaps, neither in the party affiliation nor the area that they live in, each individual lives in exactly one location and belongs to exactly one party. We see that if we add together party A and B to get 20 or all 4 regions are equal to 20. As we are asked, how many subcommittees of this legislative committee are possible that contain exactly 1 member from each of the 4 regions and the SAME (equal) number of members from each of the 2 political parties, we need to account for all possibilities. So what does this question mean? We need to have each region present. However, we have a constraint: the same number of members from each party, meaning we need 2 from each. So one of our possible combination could look something like this: 5C1*1C1*0C1*3C1. However, the constraints of the task don't actually allow us to do this as then we wouldn't have 4 people in total. As in party B not all regions are available, we best start with party B and provide 3C2 possible combinations for party B (3) instead of 4C2 (6) if all regions were filled. Now, if we choose 2 regions in party B, we need to choose the not chosen 2 for party A. So our combinations are (leaving out combination notation as xC1=x): 2*4*3*2+2*3*1*3+4*3*5*3=246­
User avatar
anushree01
Joined: 06 Apr 2024
Last visit: 02 Sep 2026
Posts: 251
Own Kudos:
90
 [4]
Given Kudos: 181
Products:
Posts: 251
Kudos: 90
 [4]
3
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
what a hard Qn is this! Firstly the language & secondly the method
Doing it under time pressure is a big thing!!!
User avatar
ItsMeHudd
Joined: 30 Jul 2026
Last visit: 01 Sep 2026
Posts: 3
Given Kudos: 1
Posts: 3
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Thank you for the in depth response, my question is how do you recognize when to multiply and when to add your possible combinations?
Bunuel


Deconstructing the wording, we find that we need subcommittees with one member from each of the four regions, resulting in exactly four members, of which two are from Party A and two from Party B.

Since Party B has fewer members and they reside in fewer regions, let's construct the subcommittees starting with Party B first. As Party B must delegate one member from each region it is represented in, we have the following scenarios for Party B's delegation:


1. From North and South;
2. From North and East;
3. From South and East.

Let's count the possibilities:

1. Party B delegates one member from North and South: this can be done in 2*4 = 8 ways. In this case, Party A should delegate from West and East: this can be done in 3*2 = 6 ways. Total for this case = 8*6 = 48;

2. Party B delegates one member from North and East: this can be done in 2*3 = 6 ways. In this case, Party A should delegate from South and West: this can be one in 1*3 = 3 ways. Total for this case = 6*3 = 18;

3. Party B delegates one member from South and East: this can be done in 4*3 = 12 ways. In this case, Party A should delegate from North and West: this can be done in 5*3 = 15 ways. Total for this case = 12*15 = 180.

Total = 48 + 18 + 180 = 246.

Answer: D.
User avatar
egmat
User avatar
e-GMAT Representative
Joined: 02 Nov 2011
Last visit: 02 Sep 2026
Posts: 6,287
Own Kudos:
Given Kudos: 715
GMAT Date: 08-19-2020
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 6,287
Kudos: 33,890
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi ItsMeHudd,

The solutions above may look different but all run on one rule.

Multiply = "AND" (choices that all happen together). You multiply when a sequence of choices must all happen to build one complete outcome.

Take Case 3 above, Party B from South and East, Party A from North and West:

- 1 of 5 from North AND 1 of 3 from West AND 1 of 4 from South AND 1 of 3 from East
- All four picks are needed for one subcommittee: 5 · 3 · 4 · 3 = 180

Add = "OR" (separate, mutually exclusive scenarios). You add when you have different non-overlapping scenarios and any one of them counts as a valid outcome. You are not doing them together, you are listing alternatives.

That is why the three cases get added: Party A comes from North, OR from South, OR from East. They cannot overlap, since only one Party-A region is possible per subcommittee. So 180 + 18 + 48 = 246.

The quick test. Ask: to finish one outcome, do I still need to make another choice? Yes means multiply. Is this instead a completely separate route to a valid outcome? Then add.

A tiny parallel. With 3 shirts and 2 pants, one outfit needs a shirt AND pants: 3 · 2 = 6 outfits. But to wear one item on your head, owning 3 hats OR2 caps gives 3 + 2 = 5 choices. "Together" multiplies, "instead" adds.

Answer: D

ItsMeHudd
Thank you for the in depth response, my question is how do you recognize when to multiply and when to add your possible combinations?

Moderator:
Math Expert
113060 posts