"Average and Weighted Average" PPT Courseware 2

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"Average and Weighted Average" PPT Courseware 2

When calculating the weighted average based on the frequency distribution table, it is commonly used in statistics that the ______ of each group represents the actual value of each group, and the ______ of each group is regarded as the weight of the median value of the corresponding group.

1. (4 points) Among the following sets of data, the group median is not 10 ()

A． 0≤x<20　B． 8≤x<12C． 7≤x<13 D． 3≤x<7

2. (4 points) Divide a certain sample data into 8 groups after analysis and sorting, and the group interval is 5. When drawing a frequency distribution line chart, find that the group median value of a certain group is exactly 18. Then the group is ()

A． 10.5～15.5 B． 15.5～20.5

C. 20.5～25.5 D. 25.5～30.5

3. (4 points) There are 4 groups in the frequency distribution histogram of a certain sample. The median values ​​of the groups from left to right are 5, 8, 11, 14, and the frequencies are 5, 4, 6, 5. Then the frequency is A group of 0.2 is ()

A． 6.5～9.5 B. 9.5～12.5

C. 8～11 D． 5～8

【Error-prone Inventory】

[Example] When Xiaoling used a calculator to find the average of 30 data, she mistakenly entered one of the data, 205, as 25. Then the difference between the calculated average and the actual average is ()

A． 3B. －3　C． 6 D． -6

【Incorrect interpretation】C

[Error Cause Analysis] Because the missing data input is 180, the calculated average is 6 less than the actual average.

【correct】

11. (12 points) After counting the number of times the class skipped rope in 60 seconds, the sports committee member drew the following two statistical graphs. Based on the information in the graph, how many times did the class skip rope on average in 60 seconds?

The average number of times the class can jump rope in 60 seconds is

(70×4%+90×8%+110×40%+130×24%+150×14%+170×8%+190×2%)÷(4%+8%+40%+24%+14%+8%+2%)＝123.6( Second-rate)

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"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: 2024-10-04

This template belongs to Mathematics courseware Hebei Education Edition Ninth Grade Mathematics Volume 1 industry PPT template

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