"Weighted Average" PPT Courseware 3

Description

"Weighted Average" PPT Courseware 3

Concept: weighted average

Generally, if among k numbers, x1 appears w1 times, x2 appears w2 times, ..., xk appears wk times (at this time w1+w2+...+wk=n), then the weighted average of these n numbers for

In a set of data, w1/n, w2/n, w3/n,...wk/n are called the weights of these k data.

Example 1: In order to examine the height of 12-year-old boys in the county, 240 people were selected and their heights (unit, centimeters) were measured as shown in the table below

Calculate the mean of this sample and estimate the average height of 12-year-old boys in the county

Solution: The average height of a 12-year-old boy is (140×2+141×10+142×16+143×56+144×70+145×56+146×20+147×8+148×2)÷240=144 (centimeter)

Answer: The average height of 12-year-old boys in the county is 144 (cm)

Example 2: The school’s small press team plans to recruit a young reporter. Three candidates, Xiaoying, Xiaoliang and Dagang, were tested on their final exam results, on-site essay competition, and oral expression ability. Their scores were as follows:

(1) If the ratio of 4:4:2 is determined and the total personal scores of the three candidates are calculated, who should be admitted based on their scores?

(2) If you want to recruit a reporter with strong oral expression skills, and the score is determined according to the ratio of 2:3:5, calculate the total personal score of the three candidates. Based on their scores, who should be admitted?

weighted average

Main knowledge content:

If there are n numbers x1, x2, x3,..., the importance of xn is expressed in continuous ratios:

f1; f2; f3;······, fn Then f1, f2, f3,······fn are called weights

The weighted average of these n numbers is:

x1f1+x2f2+···+xnfn/f1+f2+······,+fn

The "right" of data can reflect the relative "importance" of the data.

The difference and connection between the arithmetic mean and the weighted average are:

1. The arithmetic mean is a special case of the weighted average (it is special in that the weights of each item are equal).

2. When the weights of the various items are not equal in actual problems, the weighted average must be used to calculate the average; when the weights of the items are equal, the arithmetic mean must be used to calculate the average. The two cannot be confused.

summary

What knowledge have you learned? What questions do you still have?

Operation:

Matching questions 1 to 5 on page 44; questions 1, 2, and 3 on page 45.

Keywords: Weighted average teaching courseware, Qingdao edition eighth grade mathematics volume PPT courseware download, eighth grade mathematics slide courseware download, weighted average PPT courseware download, .PPT format;

For more information about the "Weighted Average" PPT courseware, please click the "Weighted Average ppt" tab.

"Average and Weighted Average" PPT courseware 3:

"Average and Weighted Average" PPT courseware 3 (1) Observation and thinking Divide an experimental field into 8 equal areas, each 100m2, and try to plant two different varieties of wheat under the same conditions of soil fertility, fertilizer, management, etc. , the output is as follows: 1. From Figure 261..

"Average and Weighted Average" PPT Courseware 2:

"Average and Weighted Average" PPT Courseware 2 When calculating the weighted average based on the frequency distribution table, the ________ of each group is commonly used in statistics to represent the actual value of each group, and the ______ of each group is regarded as the value in the corresponding group The right of value. 1. (4 points) Among the following sets of data, in the group...

"Average and Weighted Average" PPT courseware:

"Average and Weighted Average" PPT courseware 1. Generally, we call the ratio of the sum of n numbers x1, x2, and xn to n the arithmetic mean of these n numbers. The abbreviated mean is recorded as x and pronounced as x. 2. The importance of each data in a set of data is not necessarily the same...

File Info

Update Time: 2024-09-09

This template belongs to Mathematics courseware Qingdao Edition Eighth Grade Mathematics Volume 1 industry PPT template

Preview