1, 2, 3, 4, 4, 5, 5, 6, 6, 7, 8, 9, in descending order.

One * * * is 13, where 3 is 5, 2 is 4 and 6, and the rest is 1.

The median is the middle number after these data are arranged. For example, it is now 13, and the middle number should be the seventh, so it is 5. Then if there are even numbers of data, which is the average of the middle two numbers, such as 18 data, it should be the ninth and 10 bits added and divided by 2.

The mode is the one with the highest frequency among these data, here it is 5, which appears three times. More than others, if there is the same amount of data, or each data is only once, then the pattern can be more than one or none.

Example 1: What is the pattern of a set of data: 2,2,3,3,4? (2、3)

Example 2: What is the pattern of a set of data: 1, 2, 3, 4? (no)

On average, this is to add up all the data and then divide it by the number. This is the abbreviation of mathematical average.

If it is a geometric average, all the data should be multiplied and then divided by the number.

There are other averages.

Generally speaking, the so-called average is mathematical average, also called average. All other averages should be noted in particular.

Definition of median: arrange a group of data in order of size, and take one data in the middle position (or the average value of two data in the middle) as the median of this group of data.

1. requires a median, and a set of data should be sorted by size without calculation. As the name implies, the median is the middle number (or the average of the two middle numbers). When sorting, it can be from small to large or from large to small.

2. When the number of data is odd, the median is one of this group of data; However, when the number of data is even, the number of bits is the average of the middle two data, which is not necessarily equal to one data in the group.

In a set of data, the data with the highest frequency is called the pattern of this set of data.

1. mode is the data with the highest frequency in a group of data, and it is the original data in a group of data, not the corresponding number of times. At this point, students are easily confused.

2. Sometimes there is more than one pattern in a set of data. For example, in data 2, 3,-1, 2, 1, 3, 2, 3 all appear twice, and they are all patterns of this set of data.