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Erik and Joe..

by mehrasa » Sat Sep 10, 2011 12:54 am
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...
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by mehrasa » Sat Sep 10, 2011 12:58 am
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?
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by cans » Sat Sep 10, 2011 1:03 am
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
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by Anurag@Gurome » Sat Sep 10, 2011 2:50 am
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...
Let the 3 people be E, J , and K.
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
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by rohit56 » Mon Dec 17, 2018 10:17 pm
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
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