septwibowo wrote:

chetan2u wrote:

HI..

the Q basically means that all rooms will have one boy each except 1 which will have two..

so we find ways to make that pair - 6C2.

and these ocuupants can be accomodated in the 5 rooms in 5! ways..

ans 6C2*5!

B

Dear

chetan2u , I understand how we get 6C2. However, how did u get the 5! ?

Since we have calculated the first from 5 slots, so we only left with 4 slots --> so the remaining will be 4!.

My asnwer : 6C2 * 4! (A).

What's wrong with my approach?

Hi

septwibowo,

While solving this problem we are able to choose 2 of the 6 members

A,B,C,D,E and F using 6c2(it could be AB/AE or any such combination)

Once they become room mates, we will have 5 groups, 4 individuals and 1 team(call them X)

and 5 rooms to fill them.

We can fill the people in the rooms in 5! ways as there are 5 groups(and 5 rooms)

So the final answer should be 6C2 * 5!(Option B)

Hope that help you!

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