Given an integer array `arr`, return the mean of the remaining integers after removing the smallest `5%` and the largest `5%` of the elements.

Answers within `10-5` of the actual answer will be considered accepted.

Example 1:

    Input: arr = [1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3]
    Output: 2.00000
    Explanation: After erasing the minimum and the maximum values of this array, all elements are equal to 2, so the mean is 2.

Example 2:

    Input: arr = [6,2,7,5,1,2,0,3,10,2,5,0,5,5,0,8,7,6,8,0]
    Output: 4.00000

Example 3:

    Input: arr = [6,0,7,0,7,5,7,8,3,4,0,7,8,1,6,8,1,1,2,4,8,1,9,5,4,3,8,5,10,8,6,6,1,0,6,10,8,2,3,4]
    Output: 4.77778

Constraints:

- `20 <= arr.length <= 1000`
- `arr.length` is a multiple of `20`.
- `0 <= arr[i] <= 105`