Answer:
There are 44 derangements of the hats.
Step-by-step explanation:
Solution:-
- A derangement is a permutation of objects that leaves no object in its original position.
- The permutation 21453 is a derangement of 12345 because no number is left in its original position. However, 21543 is not a derangement of 12345, because this permutation leaves 4 fixed.
- Let Dn denote the number of derangements of n objects:
The number of derangements of a set with n elements is:
![D_n = n!* [ 1 - 1/1! + 1 / 2! - 1 /3! + ...+ (-1)^n 1/n! ]](https://tex.z-dn.net/?f=D_n%20%3D%20n%21%2A%20%5B%201%20-%201%2F1%21%20%2B%201%20%2F%202%21%20-%201%20%2F3%21%20%2B%20...%2B%20%28-1%29%5En%201%2Fn%21%20%5D)
- The answer is the number of ways the hats can be arranged so that there is no hat in its original position divided by n!, the number of permutations of n hats:
![D_5 = 5!* [ 1 - 1/1! + 1 / 2! - 1 /3! + 1 /4! - 1/5!]\\\\D_5 = 44 ways](https://tex.z-dn.net/?f=D_5%20%3D%205%21%2A%20%5B%201%20-%201%2F1%21%20%2B%201%20%2F%202%21%20-%201%20%2F3%21%20%2B%201%20%2F4%21%20-%201%2F5%21%5D%5C%5C%5C%5CD_5%20%3D%2044%20ways)
- There are 44 derangements of the hats.