Question

You need to put your reindeer, Prancer, Quentin, Rudy, and Jebediah, in a single-file line to pull your sleigh. However, Rudy and Prancer are best friends, so you have to put them next to each other, or they won't fly. How many ways can you arrange your reindeer?

Answer 1

12 Khan academy

Explanation:

Answer 2

Answer: 12 ways.

Explanation:

We need to put your reindeer, Prancer, Quentin, Rudy, and Jebediah, in a single-file line to pull sleigh.

Here , Total reindeer= 4

However , Rudy and Prancer are best friends, so to put them together we consider their pair as one, total objects to arrange = (Rudy and Prancer )(Quentin) (Jebediah) =3

Total ways to arrange 3 things = 3! [By permutations]

Also, Rudy and Prancer can be arranged in 2 ways.

So , total ways to arrange all of them = 2 x 3! = 2 x 3 x 2 x 1 = 12

Hence, we can arrange reindeer in 12 ways.