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Arranging marbles in a circle

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by Uva@90 » Sat Jan 11, 2014 12:10 am
gmattesttaker2 wrote:Hello,

Can you please assist with this?

Mike has 5 marbles, each of a different color; in how many ways can he arrange his marbles on a circle he drew on the floor?

OA: 24


Thanks a lot,
Sri
Sri,
Arranging objects in a circle
There are (n-1)! ways to arrange n distinct objects in circle.
So here N=5
there must be 4! ways i.e. 24 ways
Answer is 24

Regards,
Uva.
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by GMATGuruNY » Sat Jan 11, 2014 3:52 am
gmattesttaker2 wrote: Mike has 5 marbles, each of a different color; in how many ways can he arrange his marbles on a circle he drew on the floor?
To count CIRCULAR arrangements:

1. Place one element in the circle.
2. Count the number of ways to arrangement the REMAINING elements RELATIVE to the first element.

In the problem above, once the first marble has been placed, the number of ways to arrange the remaining 4 marbles relative to the first marble = 4! = 24.

Trickier problem:

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