"Average" data analysis PPT courseware 3

Description

"Average" data analysis PPT courseware 3

learning target:

1. Master the concepts of arithmetic mean and weighted average, and be able to find the arithmetic mean and weighted average of a set of data.

2. Understand the connection and difference between arithmetic mean and weighted average, and be able to use them to solve some practical problems.

Key points: The concepts of arithmetic mean and weighted average; how to find the arithmetic mean and formal weighted average of a set of data.

Difficulty: How to find the weighted average.

In daily life, we often use average to express the "average level" of a set of data.

Concept 1: Generally, for n numbers x1, x2,...,xn, we call (x1+x2+...+xn)/n the arithmetic mean of these n numbers, or the average for short.

(1) The average score of A is (72+50+88)/3=70 points.

The average score of B is (85+74+45)/3=68 points.

The average score of C is (67+70+67)/3=68 points.

Since 70>68, A will be hired.

(2) The test score of A is

(72×4+50×3+88×1)/(4+3+1)=65.75 points.

B’s test score is (85×4+74×3+45×1)/(4+3+1)=75.875 points.

C’s test score is (67×4+70×3+67×1)/(4+3+1)=68.125 points.

Therefore candidate B will be hired

In practical problems, the "importance" of each data in a set of data may not be the same. Therefore, when calculating this set of data, each data is often given a "weight".

For example, 4 in Example 1 is the right of innovation, 3 is the right of comprehensive knowledge, and 1 is the right of language. And call (72×4+50×3+88×1)/(4+3+1) as the weighted average of A’s three test scores.

Extend and improve

(1) In a certain exam, the average score of 5 students is 82. Except for A, the average score of the other 4 students is 80. Then A’s score is ( )

(A)84 (B) 86 (C) 88 (D) 90

2. If the average of m numbers is x and the average of n numbers is y, then the average of these (m+n) numbers is ( )

A:(x+y)/2 B:(x+y)/(m+n) C:(mx+ny)/(x+y) D:(mx+ny)/(m+n)

3. It is known that the average of data a1, a2, a3 is a, then the average of data 2a1+1, 2a2+1, 2a3+1 is

(A)a (B)2a

(C) 2a+1 (D) 2a/3+1

Keywords: Data analysis courseware, average courseware, Beijing Normal University edition eighth grade mathematics volume 1 PPT courseware, eighth grade mathematics slide courseware download, data analysis PPT courseware download, average PPT courseware download, .ppt format

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Update Time: 2024-10-29

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