Mean of Array After Removing Some Elements

# 1619. Mean of Array After Removing Some Elements

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
 ```

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

/**
 * @param {number[]} arr
 * @return {number}
 */
 var trimMean = function(arr) {
    arr.sort((a, b) => a - b);
    const numCnt = arr.length;
    const fivePercent = 0.05 * numCnt;
    let sum = 0;
    for (let i = fivePercent; i < numCnt - fivePercent; i++) {  
        sum += arr[i];
    }

    return sum / (numCnt - 2 * fivePercent);
};