According to statistics, when calculating the average value and other indicators in statistics, the value that weights the values of each variable is called weight.

Example: Average the following series of numbers.

3、4、3、3、3、2、4、4、3、3、

The general solution is (3+4+3+3+2+4+4+3+3)/10 = 3.2.

The weighted solution is (6 * 3+3 * 4+2)/ 10 = 3.2.

Among them, 3 appeared 6 times, 4 appeared 3 times and 2 appeared 1 time. 6,3 and 1 are called weights. This method is called weighting method.

Generally speaking, the average is to add up all the numbers and divide them by the total. Expressed as: (p1+p2+P3+..+pn)/n;

However, some data records have some of the same data. When calculating, if there are several identical numbers in that number, multiply this number by several. This number is called weight and weighting, which is multiplied by several and then added. The average is still divided by the total.

Let's take the above numbers as an example: each number has some identical numbers, which are respectively expressed as: k 1, k2, k3.kn

The formula of weighted average is: (k1p1+k2p2+k3p3+kpn)/(k1+k2+k3+.. kn).