Three people are to be seated on a bench. How many different sitting arrangements are possible if Erik must sit next to Joe?
it is easy Q but i am a bit confused when i am going to solve easier Qs based on more challenging Qs i tried to underestand in probability and combination... to me the approach is 3!/2! = 3 ways
while the answer is 4 ways...
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Erik and Joe..
This topic has expert replies
-
mehrasa
- Master | Next Rank: 500 Posts
- Posts: 279
- Joined: Fri Nov 05, 2010 5:43 pm
- Thanked: 15 times
- Followed by:1 members
when i want to solve it without formula i can figure out where this four come
let,s say the third name is kevin.. different arrangement are as follows:
JEK
EJK
KEJ
KJE
could u plz tell me how I can find it with formula?
let,s say the third name is kevin.. different arrangement are as follows:
JEK
EJK
KEJ
KJE
could u plz tell me how I can find it with formula?
-
cans
- Legendary Member
- Posts: 1309
- Joined: Mon Apr 04, 2011 5:34 am
- Location: India
- Thanked: 310 times
- Followed by:123 members
- GMAT Score:750
let persons by k,e,j.
e and j sit together, so put them in a box.
Now we have 'k' and a box. no. of ways to arrange them = 2!
Now in between box, we can arrange e,j in 2 ways: (ej,je)
thus 21*2 = 4 ways
e and j sit together, so put them in a box.
Now we have 'k' and a box. no. of ways to arrange them = 2!
Now in between box, we can arrange e,j in 2 ways: (ej,je)
thus 21*2 = 4 ways
If my post helped you- let me know by pushing the thanks button 
Contact me about long distance tutoring!
[email protected]
Cans!!
Contact me about long distance tutoring!
[email protected]
Cans!!
GMAT/MBA Expert
-
Anurag@Gurome
- GMAT Instructor
- Posts: 3835
- Joined: Fri Apr 02, 2010 10:00 pm
- Location: Milpitas, CA
- Thanked: 1854 times
- Followed by:523 members
- GMAT Score:770
Let the 3 people be E, J , and K.mehrasa wrote:Three people are to be seated on a bench. How many different sitting arrangements are possible if Erik must sit next to Joe?
it is easy Q but i am a bit confused when i am going to solve easier Qs based on more challenging Qs i tried to underestand in probability and combination... to me the approach is 3!/2! = 3 ways
while the answer is 4 ways...
Now since E must sit next to J, so treat them as 1 person.
So, the possible arrangements are 2!
Now, E and J can also interchange places among themselves, which can be done in 2 ways (EJ and JE)
So, the possible no. of sitting arrangements are 2! * 2 = 4 ways
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Consider Eric and joe as one person. Then we have total 2 persons to be seated.
No of ways of doing so = 2 ways
Now, Eric and joe could also be arranged in 2 different ways i.e Erik left to Joe and Erik right to Joe.
Hence, total ways = 2 x 2 = 4
No of ways of doing so = 2 ways
Now, Eric and joe could also be arranged in 2 different ways i.e Erik left to Joe and Erik right to Joe.
Hence, total ways = 2 x 2 = 4
