"Range and Variance" Data Analysis PPT Courseware 2

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"Range and Variance" Data Analysis PPT Courseware 2

review

1. The variance of data 0, -3, 1, -2, -3, 2, 3 is ( )

A -3 B 3

C -6 D 6

2. Two basketball players compete in a shooting competition. If the variance of athlete A’s scores is 0.12 and the variance of athlete B’s scores is 0.079, it is estimated that ____’s scores are more stable than ____’s scores.

induction

How to use statistics:

Many practical problems can be solved with statistical knowledge. When you want to make the best choice among several different options, you must first clarify the purpose of choosing the option, then consider the entry point of the problem and select appropriate statistics to compare, so as to make the right choice.

practise

A 74 74 75 74 76 73 76 73 76

75 78 77 74 72 73

B 75 73 79 72 76 71 73 72 78

74 77 78 80 71 75

Which agricultural and sideline products processing factory do you think fast food companies should choose to produce chicken legs?

consolidate

1. Two machine tools A and B produce a kind of part at the same time. In 10 days, the number of defective products produced by the two machine tools every day is

A 0 1 0 2 2 0 3 1 2 4

B 2 3 1 1 0 2 1 1 0 1

(1) Calculate the mean and variance of the two sets of data respectively;

(2) Judging from the calculation results, which machine tool produced the smaller average number of defective products in 10 days? Which machine tool has less fluctuation in defective products?

practise:

1. In the calculation formula of variance

S2=1/10[(x1-20)2+(x2-20)2+....+(x10-20)2], the numbers 10 and 20 respectively represent ( )

A. Sample capacity and variance B. Mean and sample capacity

C. Capacity and mean of the sample D. Variance and mean of the sample

illustrate:

①The average is an indicator that reflects the overall trend of a set of data, and the variance is an indicator that indicates the degree of dispersion of a set of data. Therefore, the variance should be used in (2).

②The steps for calculating the variance can be summarized as "average first, then find the difference, square it, and then average".

Example 3. (P144——Question 3.) In order to examine the growth of wheat A and wheat B, 10 seedlings were extracted from them respectively, and the seedling heights were measured as follows (unit: cm):

A: 12 13 14 15 10 16 13 11 15 11

B: 11 16 17 14 13 19 6 8 10 16

Which type of wheat grows more neatly?

Thinking: What are the general steps to find the variance of data?

1. Find the average of the data;

2. Use the variance formula to find the variance.

Please use your findings to solve the following problems:

It is known that the mean of data a1, a2, a3,...,an is X and the variance is Y, then

①The average of data a1+3, a2 + 3, a3 +3,..., an +3 is --------, and the variance is -------

②The average of data a1-3, a2 -3, a3 -3,..., an -3 is ----------, and the variance is --------

③The average of data 3a1, 3a2, 3a3,...,3an is -----------, and the variance is ----------.

④The average of data 2a1-3, 2a2 -3, 2a3 -3,..., 2an -3 is ----------, and the variance is ----------.

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For more information about the "Analysis of Data Range and Variance" PPT courseware, please click the "Analysis of Data ppt Range and Variance ppt" tag.

"Range and Variance" data analysis PPT courseware:

"Range and Variance" data analysis PPT courseware introduces new knowledge Range: the difference between the maximum data and the minimum data in a set of data Range = maximum value - minimum value. Function: Range can reflect the range of changes in data. Range is the simplest way to measure changes in data..

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Update Time: 2024-06-29

This template belongs to Mathematics courseware People's Education Press Eighth Grade Mathematics Volume 2 industry PPT template

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