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Re: PS : Probability ( Circular arrangement) [#permalink]
09 Oct 2003, 16:12

amarsesh wrote:

5! - 4! 6 people can be arranged in a circle in 5! ways. Considering the 2 people that need to be away as a single person, we can get the combinations that the two of them are together = 4! So, answer = 6! - 4! = 96 (if the order does not matter) = 48 (if order does matter) Amar.

Did you get it backwards. If order matters, the answer is 96.

Dont you think that in arrangements , Order always matters , unless specified

Re: PS : Probability ( Circular arrangement) [#permalink]
01 Dec 2003, 23:03

praetorian123 wrote:

In how many ways can 6 ppl be seated in a circle if 2 ppl are always separated?

There are 5! ways for 6 people to sit in a circle.

If we consider the couple as ONE unit, there are 4! ways to arrange them around the circle x 2 ways the couple can sit. Hence the answer is:

5! - 2 * 4! _________________

Best,

AkamaiBrah Former Senior Instructor, Manhattan GMAT and VeritasPrep Vice President, Midtown NYC Investment Bank, Structured Finance IT MFE, Haas School of Business, UC Berkeley, Class of 2005 MBA, Anderson School of Management, UCLA, Class of 1993

I know I'm asking a lot, but could you guys explain this problem in such a way a baby could understand it? I'm having trouble understanding the 4! * 2 part of this answer.