By taking in mind the number of combinations of 4 out of the 7 dishes, and the possible orders of these 4 dishes, we will find that there are 840 unique ways to arrange 4 of the 7 dishes.
We know that if we have a set of N elements, the total number of different combinations of K elements (K ≤ N) out of the N elements is given by:
[tex]C(N, K) = \frac{N!}{(N - K)!*K!}[/tex]
In this particular case, we have:
Then the number of different combinations is given by:
[tex]C(7, 4) = \frac{7!}{(7 - 4)!*4!} = \frac{7*6*5}{3*2} = 35[/tex]
Now we have 4 dishes selected, but we also need to order them.
The number of different arrangements of the dishes is given by the product between the numbers of options above, this gives:
4*3*2*1 = 24
Then the total number of unique ways of arranging 4 of the 7 dishes is:
C = 24*35 = 840
Where we take in mind the possible number of combinations of 4 out of the 7 dishes, and the possible orders of these 4 dishes.
If you want to learn more, you can read:
https://brainly.com/question/9976085