Given an array of integers `arr` and two integers `k` and `threshold`, return the number of sub-arrays of size `k` and average greater than or equal to `threshold`.

Example 1:

    Input: arr = [2,2,2,2,5,5,5,8], k = 3, threshold = 4
    Output: 3
    Explanation: Sub-arrays [2,5,5],[5,5,5] and [5,5,8] have averages 4, 5 and 6 respectively. All other sub-arrays of size 3 have averages less than 4 (the threshold).

Example 2:

    Input: arr = [11,13,17,23,29,31,7,5,2,3], k = 3, threshold = 5
    Output: 6
    Explanation: The first 6 sub-arrays of size 3 have averages greater than 5. Note that averages are not integers.

Constraints:

- `1 <= arr.length <= 105`
- `1 <= arr[i] <= 104`
- `1 <= k <= arr.length`
- `0 <= threshold <= 104`