Short Probability (permutation) question

[jasper10]

Homework Statement

There is a total of 19 students sitting in a semi-cirlce. How many seating arrangements are possible, if 4 of the 19 students have to sit next to each other?

The Attempt at a Solution

I'm not sure if the calculation is:

15! x 4!

or

19! / 4!

Thanks!

 

[LCKurtz]

Homework Statement

There is a total of 19 students sitting in a semi-cirlce. How many seating arrangements are possible, if 4 of the 19 students have to sit next to each other?

The Attempt at a Solution

I'm not sure if the calculation is:

15! x 4!

or

19! / 4!

Thanks!

I would go with the first answer, assuming you can explain it.