Question 2: How to calculate the original data of frequency 1 according to frequency, such as the weight records of 40 students in a class: (unit kg) 44 46 43 5 1 5 1 52. . . . . . 2 Calculate the difference between the maximum value and the minimum value of the data. For example, the maximum value is 6 1 and the minimum value is 42, and their difference is 19. Calculate the difference between the maximum and minimum values, and you will know the range of this set of data. 3 Determine the interval and number of groups, and group a batch of data. Generally speaking, there are many data and groups. When the number of data is less than 100, according to the number of data, it is often divided into 5 to 12 groups, and the distance between two endpoints in each group is called the group distance. If the group spacing is 3kg, then the maximum and minimum values/group spacing = 19/3=6. 333 is divided into 7 groups. 40 data, divided into 7 groups, the number of groups is appropriate. Some data in the four-column frequency distribution table is only the dividing point between groups, and it is stipulated that the data in each group contains the lowest value of the starting and ending range of the group. Exclude the highest value (other questions can be customized) 5 Draw the histogram of frequency distribution = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =1. Basic concept 1. Frequency: the number of data falling in different groups is like this. We usually accumulate by counting "positive" words. 2. Frequency: the ratio of frequency to total data, that is, frequency =, and the sum of each group of frequencies is 1. The frequency size reflects the weight of each group of frequencies in the total data. 3. Number of groups: The number of groups into which all samples are divided is called the number of groups. 4. Group spacing: the difference between two endpoints of each group. 2. The sum of each group of frequencies is equal to1; Total data × frequency of each group = frequency of the corresponding group. The purpose of drawing the histogram of frequency distribution is to express the results visually in the frequency distribution table, in which the distance and number of groups play a key role, and if there are too few groups, the data will be very concentrated; If there are too many groups, the data will be very scattered, covering up the distribution characteristics. When the data is within 100, it is generally divided into 5~ 12 groups. Thirdly, the feature of histogram represents the frequency of the corresponding group through the height of rectangle, which is called frequency distribution histogram. Yes: ① Clearly display the frequency distribution of each group; ② It is easy to show the difference of frequency among groups. Fourthly, the step of making frequency distribution histogram is 1. Find the maximum and minimum values in all the data and calculate their differences. Secondly, determine the interval and the number of groups. Third, determine the main points. Fourth, list the frequency distribution table. Fifth, draw the histogram of frequency distribution. Fifth, we can draw a line chart of frequency distribution on the basis of histogram and take it down first. Then take two points with frequency of 0 on the horizontal axis, which are separated from the group median of two rectangles at the left and right ends of the histogram by a set of distances, and connect these points with line segments in turn to get the frequency distribution line graph. 6. The difference between a bar chart and a histogram is 1. Bar charts represent frequency by the height of bars, while histograms actually represent frequency by the area of rectangles. When the widths of rectangles are equal, they can be rectangles. 2. In the histogram, the data on the horizontal axis is isolated and specific, while in the histogram, the data on the horizontal axis is continuous and a range; 3. In the bar chart, there are gaps between rectangles, while in the histogram, the rectangles are close together; Mathematical ideas and methods related to statistical charts 1. Combination of numbers and shapes: From the statistical chart, we can see the characteristics of each group of data, which can be further applied to solve practical problems. By sorting out the data and drawing statistical charts as required, we can further analyze the data and make decisions. 2. Analogy: Drawing a histogram of frequency distribution is similar to drawing a bar chart. If the width of a rectangle is the same, then the ratio of the height of this rectangle is the ratio of the number of data in each group.
Question 3: How to find the frequency? Frequency is the number of times an element appears in a sequence, which is called frequency.
The number of "a set of data" is called the total.
Because frequency = frequency/total
So frequency = total number of frequencies x
Frequency, also called "frequency". Refers to the number of times that a number (flag value) representing a certain characteristic appears in the variable value. The frequencies arranged in turn according to groups constitute a frequency sequence, which is used to illustrate the strength of each group of logo values on all logo values. The sum of the frequencies of each group is equal to all units of the group. The representation of frequency can be in the form of table or chart.
Question 4: How to calculate the probability, how to calculate the frequency and how to calculate the frequency P (a) = the number of samples contained in a/the number of samples contained in the population. In practice, the method of "permutation and combination" is often used to calculate?
Frequency is the number of times an element appears in a sequence, which is called frequency.
The number of "a set of data" is called the total.
Because frequency = frequency/total
So frequency = total number of frequencies x