The total area of Wisconsin is 65498 square miles. Of that, about 80% is land area. About how many square miles of Wisconsin is not land area?

13,100 mi²

Step-by-step explanation:

If 80% of the area of WI is land area, then that area is 0.80 (35,498 mi²).

If (100% - 80%), or 20%, is not land area, then that area comes to

0.20 (65,498 mi²), or 13,100 mi² (rounded up from 13,099.6).