For such questions, it helps to rewrite the list in order

For such questions, it helps to rewrite the list in order. So: 1,1,1,2,2,3,3,3,4.

The mode is the number which appears most often. Since both 1 and 3 appear three times each, the mode is both 1 and 3.

The median is the 'middle' number when the list is ranked in order. Since this list has 9 numbers, the middle number is the 5th one, which in this case is 2.

The mean is another word for average. To calculate the average, simply add up all the numbers and divide by the number of numbers in the list. In this case we have 20 divided by 9, which equals 2.22.