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Estimating the population using samples

Review of Mathematics Lesson Plan "Estimating Population with Samples"

Estimating the population with samples in class 2

I. Summary of basic knowledge review

1. Steps to make a frequency distribution histogram

(1) Find the range (ie the difference between the maximum and minimum values in a set of data).

(2) Determine the group distance and the number of groups.

(3) Group the data.

(4) Column frequency distribution table.

(5) Draw a histogram of frequency distribution.

2. Frequency distribution line graph and overall density curve

(1) Line chart of frequency distribution:

Connect the midpoints of the upper ends of the small rectangles in the frequency distribution histogram to get a frequency distribution line chart.

(2) Overall density curve: As the sample size increases, the number of groupings increases and the group spacing decreases. The corresponding frequency line chart will be closer to a smooth curve. This smooth curve is called Overall density curve.

3. Stem and leaf illustration

There is also a kind of graph used to represent data in the statistics. It is called a stem-leaf graph. The stem refers to a column in the middle.

4. Standard deviation and variance

(1) Standard deviation is an average distance from sample data to the mean.

Estimating the population using samples

(2) Standard deviation: s = (3) Variance: 2222121 [() () ()] nsxxxxxxn

=-+-++-. Second, the basic concept of clearance detection

Judging the correctness of the following conclusions (correct “√” and wrong “×”)

(1) The mean, mode and median describe the central tendency of a set of data from different angles. (√)

(2) The mode of a set of data can be one or several, so the median has the same conclusion. (×)

(3) The original data content cannot be obtained from the frequency distribution histogram. After the data is expressed as a histogram, the original specific data information is erased. (√)

(4) Stem and leaf diagram Generally, the leaves on the left are written in the order of large to small, and the leaves on the right are written in small to large. The same data can be recorded only once. (×)

(5) In the frequency distribution histogram, the abscissa of the midpoint of the bottom edge of the highest rectangle is the mode. (√)

(6) In the frequency distribution histogram, the area sum of the small rectangles on the left and right of the mode is equal. (×)

(7) In the frequency distribution histogram, the height of the small rectangle indicates the frequency. (×)

(8) The sum of the areas of the rectangles in the frequency distribution histogram is 1. (√)

(9) The larger the variance of a set of data, the greater the fluctuation of this set of data. (√)

(10) The median and mode are unique. (×)

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