"Weighted Average" PPT courseware

Description

"Weighted Average" PPT courseware

learning target:

1. Recognize and understand the weights and functions of data.

2. Understand the meaning of weighted average and be able to perform relevant calculations based on the calculation formula of weighted average.

focus

Concept of weighted average and application of weighted average to problem solving.

difficulty

Understanding of the concept of data weights and their role.

Review old knowledge

Can you find the arithmetic mean (referred to as the mean) of a set of data 1, 2, 3, 4, 5, 6, and 7?

Can you express this calculation process in words?

To find the average of a set of data, you divide the sum of all the data in the set by the number of pieces in the set.

Open wisdom

In order to meet the needs of customers, a shopping mall mixed 15kg of toffee, 3kg of puff pastry and 2kg of plum candy into assorted candies for sale. It is known that the selling price of toffee is 40 yuan per kilogram, the price of crisp candy is 20 yuan per kilogram, and the price of plum candy is 15 yuan per kilogram. How much should the mixed sugar be sold for per kilogram?

Xiao Liang believes that the selling price per kilogram of mixed sugar is the average of the unit prices of the three sugars, that is

40+20+15/3=25

Xiaoying believes that the masses of the three sugars in the population are not equal. When calculating the selling price of each kilogram of assorted sugar, the total price of the three sugars after mixing should be found, and then divided by their total mass, that is

40×15+20×3+15×2/15+3+2=34.5

Whose algorithm do you agree with? Communicate with classmates

analysis Summary

In the above question, 5 people have a daily output of 20 pieces, 8 people have a daily output of 21 pieces, and 9 people have a daily output of 25 pieces. In other words, among the 100 data of workers' daily output, data 20 appears 5 times, data 21 appears 8 times, and data --------25 appears 9 times.

Frequency: In a set of data, the number of times a piece of data appears repeatedly is called the frequency of the data.

Can you tell the frequency of the data 22, 23, and 24 in the above question?

think about it

1. In order to examine the average height of 12-year-old boys in the county, 240 people were randomly selected and their heights (unit: cm) were measured as shown in the following table:

Calculate the mean of this sample (accurate to 1 cm) and therefore estimate the average height of 12-year-old boys in the county.

2. The school’s small reporter team recruits a young reporter in the eighth grade. The recruitment method is: each person provides the average score of each subject in the final exam of the previous semester, and conducts an on-site composition competition and oral expression ability test. The three scores of the applicant are calculated according to the ratio of 4:4:2. The total score of the worker is calculated and the recruitment is based on the score. The following table shows the scores of three candidates, Xiaoying, Xiaoliang, and Xiaogang. What are their total personal scores in the test?

practice

In the school health inspection, it is stipulated that the classroom hygiene score of each class accounts for 30%, the environmental sanitation score accounts for 40%, and the personal hygiene score accounts for 30%. The scores of these three scores for the eighth grade class are 85 points, 90 points, and 95 points respectively. , find the total score of the class's health inspection.

Summary

1. Average

2. Weighted average

3. Application of weighted average

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;

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"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...

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Update Time: 2024-10-19

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

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