Q&A: permutation problem!!!!?
Question by liangjizong22: permutation problem!!!!?
The United Nations celebrates a certain international holiday by displaying four Belgian flags, two Argentinean flags, and three south Korean flags. If the Argentinean flags must be on either end, how many possible arrangements are there??
please explain with thorough details
In each case, solve for x.
xP5=1
well, I know the answer is 5, but still feel uncomfortable with it until I will have the whole idea. thanks.
Best answer:
Answer by Ancient Mariner
Well, I don’t have a maths degree, but even I can tell ther are more than 5 possibilities.
As the outside flags are always Argentinian, we can ignore them. The first flag can be either of 2 possibilities, as can the second and third at least, maybe even the fourth. thus we have 2x2x2x2 permutations =16.
Using A for Argentinian, B for Belgian and K for South Korean, the following possibilities are all different and not the reverse of any other.
ABBBBKKKA
ABBBKBKKA
ABBBKKBKA
ABBBKKKBA
ABBKBBKKA
ABBKBKBKA
ABBKBKKBA
ABBKKBBKA
ABBKKBKBA
ABBKKKBBA
ABKBBBKKA
ABKBBKBKA
ABKBBKKBA
ABKBKBBKA
ABKBKBKBA
ABKKBBBKA
As to the formula, sorry can’t help.
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