What are mean, standard deviation and relative number?

What are mean, standard deviation and relative number?

Mean is the sum of all data in a group of data and then divided by the number of data. It is an indicator reflecting the trend of data set. Standard deviation, also known as mean square error, is the average of the distance of each data from the average, which is the square root of the sum of the squares of the deviation from the average, The standard deviation is the arithmetic square root of variance. The standard deviation can reflect the degree of dispersion of a data set. If the mean is the same, the standard deviation may not be the same. The general relative number is the ratio of two related indexes, which can quantitatively reflect two related indexes
There are many kinds of relative numbers, which can be divided into two types according to their manifestations: one is nominal number, that is, the relative number calculated by comparing two absolute numbers or average numbers with different properties and connections, which generally has nominal number and uses compound measurement unit; the other is nameless number, Nameless number can be expressed by multiple, percentage, coefficient, percentage, thousand score, etc. according to different situations, such as birth rate, death rate, etc

In N numbers, if the largest number is equal to their average number, the standard deviation of N numbers is ()
If the largest number is equal to the average, why are all numbers equal to the average?

The average is the balance between the large number and the decimal. If the largest number is the average, then all numbers are equal to the average, because if there is a number smaller than the average, there must be a larger number to complement, but there is no number larger than the average, so there is no number smaller than the average. Then the standard deviation of a group of equal numbers should be equal to 0

Writing and reading of all symbols in Higher Mathematics

Common mathematical symbols and the meaning of the main mathematical symbols - reprint capital and small English phonetic alphabet international phonetic alphabet phonetic alphabet Chinese phonetic alphabet alpha alpha alpha alpha alpha alpha alpha alpha alpha alpha alpha alpha alpha alpha beta beta beta beta beta gamma gamma delta delta delta delta delta Ε ε