|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Updated on: 14 Oct 2013, 07:06
Originally posted by praffulpatel on 14 Oct 2013, 07:05.
Last edited by Bunuel on 14 Oct 2013, 07:06, edited 1 time in total.
Last edited by Bunuel on 14 Oct 2013, 07:06, edited 1 time in total.
RENAMED THE TOPIC.
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
81% (00:33) correct
19%
(00:56)
wrong
based on 334
sessions
History
Date
Time
Result
Not Attempted Yet
A group of six friends sit together and form a circle. They will be playing a game that involves asking a fun question to the person to his/her left. How many ways can this game be played? In other words, how many ways can these six friends arrange themselves in a circle?
(A) 6
(B) 24
(C) 32
(D) 120
(E) 720
(A) 6
(B) 24
(C) 32
(D) 120
(E) 720
14 Oct 2013, 07:08
Kudos
Bookmarks
praffulpatel
We have a case of circular arrangement.
The number of arrangements of n distinct objects in a row is given by \(n!\).
The number of arrangements of n distinct objects in a circle is given by \((n-1)!\).
From Gmat Club Math Book (combinatorics chapter):
"The difference between placement in a row and that in a circle is following: if we shift all object by one position, we will get different arrangement in a row but the same relative arrangement in a circle. So, for the number of circular arrangements of n objects we have:
\(R = \frac{n!}{n} = (n-1)!\)"
\((n-1)!=(6-1)!=120\)
Answer: D.
Questions about this concept to practice:
seven-men-and-seven-women-have-to-sit-around-a-circular-92402.html
a-group-of-four-women-and-three-men-have-tickets-for-seven-a-88604.html
the-number-of-ways-in-which-5-men-and-6-women-can-be-seated-94915.html
in-how-many-different-ways-can-4-ladies-and-4-gentlemen-be-102187.html
4-couples-are-seating-at-a-round-tables-how-many-ways-can-131048.html
at-a-party-5-people-are-to-be-seated-around-a-circular-104101.html
seven-family-members-are-seated-around-their-circular-dinner-102184.html
seven-men-and-seven-women-have-to-sit-around-a-circular-11473.html
a-group-of-8-friends-sit-together-in-a-circle-alice-betty-106928.html
seven-men-and-five-women-have-to-sit-around-a-circular-table-98185.html
a-group-of-8-friends-sit-together-in-a-circle-alice-betty-106928.html
find-the-number-of-ways-in-which-four-men-two-women-and-a-106919.html
gmat-club-monday-giveaway-155157.html (700+)
Hope it helps.
General Discussion
06 Jun 2015, 16:41
Kudos
Bookmarks
Hi All,
The logic behind these types of permutation questions is easy to explain if you have a picture to look at...so if you're 'stuck' on this type of permutation concept, then here's how to think about it.
First, if we had 6 people standing in a row, then there would be 6! = 720 ways to arrange those people.
When putting them into a circle though, any of the 6 spots could be the "first spot"....To visualize this, draw a circle, then place 6 people on it (call the people A, B, C, D, E and F). If you rotate the picture, the 6 people remain in the same respective arrangement, so you're not allowed to count all of those orientations as separate possibilities. Since any of the 6 spots could be the "first spot", you have to divide your total options by 6...
720/6 = 120 different arrangements.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
The logic behind these types of permutation questions is easy to explain if you have a picture to look at...so if you're 'stuck' on this type of permutation concept, then here's how to think about it.
First, if we had 6 people standing in a row, then there would be 6! = 720 ways to arrange those people.
When putting them into a circle though, any of the 6 spots could be the "first spot"....To visualize this, draw a circle, then place 6 people on it (call the people A, B, C, D, E and F). If you rotate the picture, the 6 people remain in the same respective arrangement, so you're not allowed to count all of those orientations as separate possibilities. Since any of the 6 spots could be the "first spot", you have to divide your total options by 6...
720/6 = 120 different arrangements.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
