"Simple Random Sampling" PPT Courseware 3

Description

"Simple Random Sampling" PPT Courseware 3

Questions raised

In order to understand the participation of students in sports activities during the summer vacation, the school is going to select a group of students for a survey. Do you think the results obtained according to the following survey method can reflect the general situation of the entire school's students? If it cannot be reflected, how should the investigation methods be improved?

Method 1: Survey 30 students on the school track and field team

Method 2: Survey male students in each class

Method 3: Select 1 student from each class for investigation

Method 4: Select half of the students in each class to conduct the survey

The meaning of simple random sampling:

In order to obtain results that can objectively reflect the problem, it is usually based on the principle that each individual in the population has the same chance of being selected. This method of extracting samples is called simple random sampling.

Note: Random sampling does not mean random or random selection, because random or casual sampling will have subjective or objective influencing factors.

Thinking: What are the main characteristics of simple random sampling?

(1) The overall number of individuals is limited;

(2) Samples are extracted one by one, and only one individual is selected at a time;

(3) Each individual has an equal chance of being selected, and sampling is fair.

Example 1: The following sample extraction method belongs to simple random sampling ( )

① Select 100 individuals as samples from infinite individuals;

② There are 80 parts in the box, and 5 parts are selected for quality inspection. During the sampling operation, any part is taken out for quality inspection and then put back into the box;

③ Randomly select 2 computers from 8 computers without replacement for quality inspection (assuming that 8 computers have been numbered, randomly select the numbers)

A.① B.② C.③ D. None of the above are correct

Consolidation exercises:

①Is the following survey a simple random sampling survey?

A. In order to understand the recitation of a certain poem by the students in this class, the Chinese teacher randomly selected 8 students to recite it;

B. The school sports meeting will hold the ninth-grade boys’ 4×100-meter relay race, and the track for each class will be determined by drawing lots;

C. In order to understand the learning burden of all students in Grade 9 (1), the class teacher only conducts inquiries among the class committee of this class;

Do it

In order to estimate how many fish there are in the pond, we catch an appropriate amount of fish from the pond, for example, 100 fish, mark them, and then put them back into the pond. After a period of time, the marked fish are completely mixed with the fish group. , and then catch a second batch of 200 sample fish. If there are 25 tagged fish among them, how many fish are estimated to be in the pond?

think about it

A melon farmer used greenhouse cultivation technology to grow high-quality watermelons on one acre of land. There were about 600 watermelons on this acre of land. Before the watermelons were put on the market, the farmer randomly picked 10 watermelons. The quality was rated as follows:

(1) Calculate the average mass of these 10 watermelons, and based on the calculation results, estimate how many kilograms of watermelon yield this mu of land will produce?

(2) What do the population, individual, and sample refer to in the above questions?

(3) What investigation methods were used in the above questions?

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"Simple Random Sampling" PPT courseware 2:

"Simple Random Sampling" PPT Courseware 2 Statistics Statistics: The study of quantitative characteristics and quantitative relationships of objective things. It is a science about the collection, sorting, induction and analysis methods of data. The basic idea of ​​statistics: Use samples to estimate the population, that is, usually without directly studying...

"Simple Random Sampling" PPT courseware:

"Simple Random Sampling" PPT Courseware Communication and Discovery In order to understand the participation of students in sports activities during the summer vacation, the school is going to select a part of the students for a survey. Do you think the results obtained according to the following survey method can reflect the general situation of the entire school's students...

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Update Time: 2024-11-25

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

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