"Median" PPT courseware 2

Description

"Median" PPT courseware 2

Median definition:

After a set of data is arranged from large to small or small to large, the data in the middle is called the median of the set of data.

(1) If the data contains an odd number, the number in the middle is the median;

If the data contains an even number, the average of the two middle numbers is the median.

(2) The unit of the median is the same as the unit of the data;

Discuss

General steps for finding the median:

1. Arrange this set of data from small to large (or from large to small);

2. If the data contains an odd number, the number in the middle is the median;

If the data contains an even number, the average of the two middle numbers is the median.

1. Find the median of each set of data below.

(1)2 4 5 4 3

Median: 4

(2)9 28 15 2 7 12

Median: 10.5

(3)34 30 28 24 20 19 17

Median: 24

3. The difference between average and median

the difference:

When calculating the average, all data are involved in the calculation. It can make full use of the information provided by the data, but it is easily affected by extreme values ​​(larger or smaller numbers). But it is the most widely used.

The advantage of the median is that it is simple to calculate and only depends on its position in the data. Not affected by extreme values. But not all data information can be fully utilized.

Reflect and expand

1. Among the following statements:

(1) There is only one median in a set of data.

(2) The median in a set of data may or may not be one in this set of data.

(3) In a set of data, the number of data greater than the median is equal to the number of data less than the median.

The correct statements are (1) (2).

2. The average of known data 1, 3, 2, x, 2

is 3, then the median of this set of data is 2.

3. A set of data 23 27 20 18 x 12, its median is 21, then the value of x is 22.

Review this lesson:

What have you gained?

Whether it is the median we know today or the average we have learned before, they are actually just a method of data representation and a perspective from which to look at problems. In the face of complicated things, we still need to keep our eyes open, choose carefully, and conduct specific analysis on specific issues.

1. If in a set of data, 23, 25, 28, 22

The number of occurrences is 2, 5, 3, and 4 times, and there is no other data, then the medians of this set of data are ( )

A.26 B.24

C.25 D.27

2. The mathematics teacher assigned 10 multiple-choice questions. The class representative drew the answers of the whole class into a bar chart. According to the chart, the median number of questions answered correctly by each student in the class was ( )

What can the median of this set of data be?

6 8 10 18 a

If 8 is the median, a can be (a≤8)

If 10 is the median, a can be (a≥10)

If a is the median, a can be (8≤a≤10)

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Update Time: 2024-10-04

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

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