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# In how many ways can 4 identical red balls and 5 different

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Senior Manager
Joined: 05 Aug 2005
Posts: 414
Followers: 1

Kudos [?]: 12 [0], given: 0

In how many ways can 4 identical red balls and 5 different [#permalink]  20 Oct 2005, 18:45
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
In how many ways can 4 identical red balls and 5 different green balls be arranged in a line such that no two red balls are together?
5*5!
5*4!*5!
6*4!*5!
6*5!
2*9!
Senior Manager
Joined: 02 Oct 2005
Posts: 303
Followers: 1

Kudos [?]: 7 [0], given: 0

I am getting answer as 5! * 5 * 4 * 4 (I guess I am missing something and it takes lot of time to get to this one). Would wait for someone to post a shorter method and the answer.
Current Student
Joined: 29 Jan 2005
Posts: 5244
Followers: 23

Kudos [?]: 179 [0], given: 0

I get 5*5!

Since the red balls are identical we can just use them as place markers.

ggrgrgrgr
grggrgrgr
grgrggrgr
grgrgrggr
rgrgrgrgg

A.
Senior Manager
Joined: 02 Oct 2005
Posts: 303
Followers: 1

Kudos [?]: 7 [0], given: 0

Senior Manager
Joined: 02 Oct 2005
Posts: 303
Followers: 1

Kudos [?]: 7 [0], given: 0

GMATT73 wrote:
I get 5*5!

Since the red balls are identical we can just use them as place markers.

ggrgrgrgr
grggrgrgr
grgrggrgr
grgrgrggr
rgrgrgrgg

A.

The following combination(s) are missing:
gRgRgRgRg
RgggRgRgR ... & so on
VP
Joined: 13 Jun 2004
Posts: 1122
Location: London, UK
Schools: Tuck'08
Followers: 7

Kudos [?]: 31 [0], given: 0

so seems it's C

not so easy this kind of problem
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