Answer:
900,900 outcomes are possible.
Step-by-step explanation:
Arrangements with repetition:
The number of possible arrangements of n elements, considered that they are divided in classes of
elements, is given by:
![A = \frac{n!}{n_1!n_2!...n_n!}](https://tex.z-dn.net/?f=A%20%3D%20%5Cfrac%7Bn%21%7D%7Bn_1%21n_2%21...n_n%21%7D)
A dancing competition has 13 competitors
This means that ![n = 13](https://tex.z-dn.net/?f=n%20%3D%2013)
Four are American, two are Mexicans, four are Russians and three are Italians.
This means that ![n_1 = 4, n_2 = 2, n_3 = 4, n_4 = 3](https://tex.z-dn.net/?f=n_1%20%3D%204%2C%20n_2%20%3D%202%2C%20n_3%20%3D%204%2C%20n_4%20%3D%203)
How many outcomes are possible?
![A = \frac{13!}{4!2!4!3!} = 900900](https://tex.z-dn.net/?f=A%20%3D%20%5Cfrac%7B13%21%7D%7B4%212%214%213%21%7D%20%3D%20900900)
900,900 outcomes are possible.