Last visit was: 18 Nov 2025, 23:53 It is currently 18 Nov 2025, 23:53
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
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 18 Nov 2025
Posts: 105,378
Own Kudos:
778,143
 [6]
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,378
Kudos: 778,143
 [6]
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
User avatar
ravigupta2912
User avatar
Current Student
Joined: 26 May 2019
Last visit: 16 Feb 2025
Posts: 726
Own Kudos:
Given Kudos: 84
Location: India
GMAT 1: 650 Q46 V34
GMAT 2: 720 Q49 V40
GPA: 2.58
WE:Consulting (Consulting)
Products:
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
nikospanayo
Joined: 10 Jan 2021
Last visit: 22 Feb 2021
Posts: 2
Own Kudos:
Given Kudos: 2
Posts: 2
Kudos: 2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
ravigupta2912
User avatar
Current Student
Joined: 26 May 2019
Last visit: 16 Feb 2025
Posts: 726
Own Kudos:
291
 [1]
Given Kudos: 84
Location: India
GMAT 1: 650 Q46 V34
GMAT 2: 720 Q49 V40
GPA: 2.58
WE:Consulting (Consulting)
Products:
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
nikospanayo
ravigupta2912
Independent events.

Each counter can be painted in x ways. Total number of counters is y

Total arrangements = y^x

Arrangements where each counter has the same colour = x

To visualise this better, i ascribed numbers 3 (x) colours for 5 (y) counters. There are only 3 possible arrangements where all the counters will have the same colour.

Therefore correct answer is y^x - x.

IMO C. Let’s see the OA.

Posted from my mobile device
i think total araangments are x^y we have y slots and each can have x different choices that gives x^y not y^x. i agrre with minus x
answer A

You’re right. My answer stands modified. I’ll consider my original post as an error.
User avatar
ScottTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 14 Oct 2015
Last visit: 18 Nov 2025
Posts: 21,712
Own Kudos:
26,994
 [2]
Given Kudos: 300
Status:Founder & CEO
Affiliations: Target Test Prep
Location: United States (CA)
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 21,712
Kudos: 26,994
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
There are counters available in x different colors. The counters are all alike except for the color. The total number of arrangements consisting of y counters, assuming sufficient number of counters of each color, if no arrangement consists of all counters of the same color is:

(A) x^y – x
(B) x^y – y
(C) y^x – x
(D) y^x – y
(E) y^x – 2y



Solution:

The first counter can be painted with x possible colors. The second counter can be painted with x possible colors. If there were just 2 counters, we would have x^2 different arrangements. If there were 3 counters, we would have x^3 different arrangements.

Since we have y counters, we see that the number of arrangements of counters is x^y, including those that have all counters the same color. However, if the counters can’t be all the same color, we need to subtract x arrangements that have all the counters the same color. That is, there are x^y - x arrangements of counters where not all of them have the same color.

Answer: A
User avatar
Fdambro294
Joined: 10 Jul 2019
Last visit: 20 Aug 2025
Posts: 1,350
Own Kudos:
Given Kudos: 1,656
Posts: 1,350
Kudos: 741
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Total number of arrangements in which the color of the counter can be repeated

=

(no. of arrangements in which counters are NOT all the same color)

+

(no. of arrangements in which counters ARE all the same color)


If there are X different color counters and Y “slots” in which the colors can be arranged, then first (assuming colors can repeat themselves)

Slot 1: X options

Slot 2: X options

Slot 3: X options

.....

All the way to Slot Y: X options

(X) multiplied by itself Y times will give us every possible arrangement in which the colors CAN be repeated ——- (X)^y


From this, we want to remove the Unfavorable Outcomes. These include the arrangements in which every “slot” has the same color counter.

If there is X different colors, the number of these arrangements will be:


1st color repeated for Y “slots”

2nd color repeated for Y “slots

....

All the way up to the Xth color repeated for Y “slots”

This means we will have exactly X arrangements in which every counter picked will be the same color.


Answer:

(X)^y - (X)

Answer A

Posted from my mobile device
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,582
Own Kudos:
Posts: 38,582
Kudos: 1,079
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
105377 posts
Tuck School Moderator
805 posts