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Permitations and combinations

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Junior | Next Rank: 30 Posts
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Permitations and combinations

by joinn » Wed Jul 06, 2011 2:24 am
Gordon buys 5 dolls for his 5 nieces. The gifts include two identical Sun-and-Fun
beach dolls, one Elegant Eddie dress-up doll, one G.!. Josie army doll, and one Tulip
Troll doll. If the youngest niece does not want the G.!. Josie doll, in how many different
ways can he give the gifts

pals please help me out how to solve this kind of problems
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by Frankenstein » Wed Jul 06, 2011 3:47 am
Hi,
The names of gifts are terrible. So, let's say the gifts are a,a,b,c,d and the nieces be p,q,r,s,t. youngest(p) doesn't want d.
_,_,_,_,_
p,q,r,s,t
p has 4 choices(all 4 except d)
remaining 4 can be arranged in 4! ways.
So, total ways is 4*4! = 96 ways
But, two things(a,a) are identical. So, we divide by 2! in the end
so, number of ways is 96/2! = 48 ways
Cheers!

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