A fancy bed and breakfast inn has 5 rooms, each with a distinctive color-coded decor. One day 5 friends arrive to spend the night. There are no other guests that night. The friends can room in any combination they wish, but with no more than 2 friends per room. In how many ways can the innkeeper assign the guests to the rooms?
A. 2100
B. 2220
C. 3000
D. 3120
E. 3125

Respuesta :

In 2220 ways the innkeeper can assign the guests to the rooms i.e. Option B is correct.

As per the question,

  • Number of rooms   =   5
  • Number of friends  =   5
  • The rooms are distinctive colour-coded decor i.e. the rooms have to be distinct.

There are Five friends and Five rooms,

⇒ 0 rooms of 2, 5 rooms of 1

⇒ 1 room of 2, 3 rooms of 1

⇒ 2 rooms of 2, 1 room of 1

Guests can be allotted rooms by the innkeeper as

              1, 1, 1, 1, 1,                 1, 2, 2,             or            1, 1, 1, 2

  • To assign ( 1, 2, 2 )  =   ways to assign guests to the rooms × ways to                                           assign frequencies to rooms

                                         =   5 × ( 4 2 ) × ( 5 2 ) ( 3 2 )

  • To assign ( 1, 2, 2 )  =   ways to assign guests to the rooms × ways to

                                              assign frequencies to rooms

                                         =   5 × 4 × 3! ( 5 2 )

  • To assign ( 1, 1, 1, 1, 1 )  =  5!      

Total number of ways ( N )  =   To assign ( 1, 2, 2 ) + To assign ( 1, 2, 2 )  +      

                                                   To assign ( 1, 1, 1, 1, 1 )

                                              =   5 × ( 4 2 ) × ( 5 2 ) ( 3 2 ) +  5 × 4 × 3! ( 5 2 ) +

                                                   5!

                                              =    5 × ( 4 2 ) × ( 5 2 ) ( 3 2 ) + 120 ( 5 2 ) + 120

                                        N   =    2220 ways    

Therefore, The innkeeper can assign guests to the rooms in 2220 ways with no more than two friends per room i.e. option B is valid.

To know more about combinations refer to:

https://brainly.com/question/2408784  

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