IIT Kanpur

Question

2. The number of different necklaces you can form with 2 black and 6 white beads is .___

Comments

Jason and  sonveer. Post your solution please.

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I also think it will be 4

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@Soumya29 refer Subarna Das's answer.

Answer 1

There will be $4$ different necklaces.

1. When $2$ black beads are separated by $4$ white beads or $2$ white beads.
2. When $2$ black beads are adjacent.
3. When $2$ black beads are separated by $1$ white beads or $5$ white beads.
4. When $2$ black beads are separated by $3$ white beads.

$\color{purple}{\text{This is in a circular permutation.}}$

So,$\color{green}{\text{ there are 4 different necklaces we can form out of 2 black beads & 6 white beads.}}$

Comments

One thing we can notice 

The above $2$ necklaces, both are same.

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Both Are Same But Selection Blacks Are Different Yes ?

4 different necklaces we can forming

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How do we do this mathematically?

Answer 2

i think 4 is right.

Comments

explain?