Question 1180815: Consider the distinct arrangements of the 12 letters in the word PALEOZOOLOGY
How many distinct arrangements have none of the 5 letters G, L, L, P, Z adjacent?
I have no idea where to start. Any help is appreciated.
Answer by Edwin McCravy(20054) (Show Source):
You can put this solution on YOUR website!
First we'll find all the distinguishable arrangements of AEOOOOY.
Then we'll insert the others G,L,L,P,Z among them so that none will be
adjacent.
There are 7!/4! = 210 distinguishable arrangements of AEOOOOY.
This could be a sample of those, putting blanks for possible places to
insert other letters
_A_E_O_Y_O_O_O_
We can pick any 2 of the 8 blanks to put the 2 L's in C(8,2)=28 ways.
Then we'd have something like this, where the x's are places where the G,P,Z
cannot go, next to either L:
_A_ExLxOxLxO_A_O_Y_
So there are P(6,3) = 120 choices of positions for G,P,Z.
Answer: 210*28*120 = 705,600
Edwin
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