In how many ways can a family of four be seated at a round table if two brothers must sit together?

Question

e.mccormick · Answer

Permiutations and factorials.  Fun!  Hmmm...  Know where to start with it?

anonymous · Answer

I tried doing 4!, but I dont think thats right

e.mccormick · Answer

This one would be with no repetition, so I think it is more like:
$$\frac{n!}{(n-r)!}$$

e.mccormick · Answer

Where r is the number of elements form n distinct elements.

anonymous · Answer

Solving...

anonymous · Answer

I have 24 but thats not an answer choice.

e.mccormick · Answer

So because the 2 must sit together, r is less than n.

anonymous · Answer

Is 4 n? Or is 2 n?

e.mccormick · Answer

Their pairing makes it a little odd.  lets see.
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For every permiutation, you have mom next to dad, but their order can change.  And you have brother next to brother, but their order can also change.  As long as they are together.