Ask for junior high school math problems, and there should be detailed steps 123 1

Estimating the population distribution with the frequency distribution of the sample [self-perception]: 1In the frequency distribution histogram, the high representation of the small rectangle (a

Frequency Sample size bGroup spacing frequency cFrequency d

Frequency Group spacing 2In the frequency distribution histogram, the area of the small rectangle is equal to ( aFrequency b. for each group of corresponding

Frequency of the corresponding groups cNumber of groups dGroup spacing 3

A sample of a certain size is taken from a group of students to analyze their academic performance, and the number of students with a score of 70 or less is known to be 8, and its cumulative frequency is , then such a sample size is ( a20 people b40 people c

70 people d80 people 4The basic way of thinking about studying statistical problems is ( a

Random sampling bUse advanced scientific calculators to calculate the frequency of the sample, etc. cControl of the production of industrial processes with the theory of small probability events d

Estimate the population with a sample of 5The following statement is correct ( aThe number of data in the sample is equal to the sum of the frequencies b

The fan chart can tell us what the number of each part is cIf a set of data can be represented by a sector chart, then it must be represented by a frequency distribution histogram dSequence the frequencies of the histogram are connected by connecting the endpoints on one side of the small rectangle to get the frequency line graph 6

A sample of capacity n, divided into groups, and the frequency and frequency of a group are known to be 40, then the value of n is a 640 d. 160 ( 7.

A sample data with a capacity of 20 is grouped with a group spacing of 10, and the distribution of intervals and frequencies is as follows: ,2; ,3; ,4; ,5; ,4; ,2.then the frequency of the sample on is ( a

b. c. d.

8 Known samples: 12,7,11,12,11,12,10,10,9,8,13,12,10,9,6,11,8,9,8,10, then the range of samples with a frequency of is ( a b.

c. d. 9.

samples with a capacity of 32, and the frequency of a certain group of samples is known, then the frequency of the group of samples is. a. 2 b.

4 c. 6 d. 8 ( 10.

In the process of random checking the size of the product, its size is divided into groups. is one of the groups, and the frequency of the individuals sampled on the group is m, and the height of the histogram on the group is h, then = (a.). b.

c. d

A value of P from 1 to 25 is possible

I would like to ask if the frequency can be greater than 1.

1) Think of x+y as a whole code chain.

Original = [(x+y)+1] 2

2) Extract this 3m and then merge the Dosen modulo dispersion subterms in parentheses.

Original = 3m[(2x-y) 2-x 2].

3m[3x^2+y^2-4xy]

9 is the bix of 3, so the second term is 2m square of 3, and so on, 27 is 3 square of 3, so it is 3m square of 3.

So 1+2m+3m=16m=3

From the vertical diameter theorem, it can be known:

D is the midpoint of AB and E is the midpoint of AC.

Then: DE is the median line of ABC.

So: bc=2de=6