标题: permuation on circles [打印本页] 作者: gocanucks 时间: 2003-5-16 06:26 标题: permuation on circles
I have got a question on permutation on circles. Say there are 5 slots, and we want to place 5 balls (different colors). What should be the correct answer? P(5) or P(5)/2.
I guess the answer depends on how one interprets whether clockwise is the same as counter-clockwise direction. What is the general assumption under GMAT? I have seen different JJ giving different answers depending on different interpretations.作者: Echo 时间: 2003-5-29 13:08
和方向无关，P(5)作者: isuffering 时间: 2003-6-2 20:34
Disucussion:
I think there're 2 tricks:
If not sonsider cloclwise or counter clockwise,
remember, it's a circle, so the ABCDE,BCDEA,CDEAB,DEBAC,EABCD is the same permutation,
then should be P(5)/5== P(4)
And
if consider cloclwise or counter clockwise,
then should be P(4)/2
Whether the clockwise permutation is considered different from or the same as the counter-clockwise permutation under the Gmat ?
It's really a question.
