1. Mean is the number you get when you add all these numbers and then divide by the number of numbers. So, (31 + 28 + 30 + 31 + 30) / 5 = 150 / 5 = 30
2. The median is the middle number in the list of numbers, so, the answer is 30 as well.
3. Mode is the number that appears most often, so here it is 30 and 31 because they both appear 2 times.
4. Range is the difference between the largest and smallest number, so 31 - 28 = 3.