"Average" data analysis PPT courseware 5

Description

"Average" data analysis PPT courseware 5

induction

Definition of arithmetic mean:

For n data x1, x2, x3,…, xn, then

It is called the arithmetic mean of these n numbers.

Representation of arithmetic mean: x=1/n(x1+x2+x3+....+xn)

Exercise 20.1

1. In order to check the length of a batch of parts, 10 pieces were taken from it and the measured lengths were as follows:

22.36 22.35 22.33 22.35 22.37

22.34 22.38 22.36 22.32 22.35

(1) What are the population, individual, sample, and sample size in this question?

(2) Estimate the average length of this batch of parts.

summary

Statistical idea: The sample mean can be used to estimate the population mean.

If the average of 4, 6, 8, x is 8, and the average of 4, 6, 8, x, y is 9, find the values ​​of x and y.

The definition of weighted average: If the weights of n data x1, x2, x3,...,xn are respectively ω1, ω2, ω3,...,ωn, then

x1ω1+x2ω2+ x3ωn....xnωn/ω1+ ω2+ω3...+ωn is called the weighted average of these n numbers.

Representation of weighted average:

x=x1ω1+x2ω2+ x3ωn....xnωn/ω1+ ω2+ω3 …+ωn

Example 1 A company plans to recruit an English translator. Two candidates A and B were tested on English proficiency in listening, speaking, reading and writing. Their scores (percentage system) are as follows:

(1) If this company wants to recruit a translator with strong oral skills, the listening, speaking, reading and writing scores are determined according to the ratio of 3:3:2:2. Calculate the average score of the two candidates and calculate it from their Based on grades, who should be admitted?

(2) If this company wants to recruit a translator with strong translation skills, the listening, speaking, reading and writing scores are determined according to the ratio of 2:2:3:3. Calculate the average score of the two candidates and calculate it from their Based on grades, who should be admitted?

Explore

(1) Admit A, (2) Admit B. Why is this?

The meaning of weight: Weight reflects the relative "importance" of data.

Class summary

1Main knowledge content:

If the weights of n numbers x1, x2, x3,…,xn are respectively ω1, ω2, ω3,…,ωn, then

x1ω1+x2ω2+ x3ωn....xnωn/ω1+ ω2+ω3...+ωn is called the weighted average of these n numbers.

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

2 Calculate the average of sample data using weighted average

3. Carefully understand the meaning of weighted average weight.

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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: 2024-09-13

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