Difficulty: 2. In a math knowledge and ability test, the average score of 42 students in Grade 8 (1) class is 78, and the average score of 48 students in Grade 8 (2) class is 8 1, so the average score of these two classes in Grade 8 is.
Difficulty: 20 1 1_ Guangxi Ke3. A school ***240 eighth-grade students took the math exam, and the teacher randomly selected 40 students' scores for statistics. * * * Excellent results are 12. According to the above data, it is estimated that some eighth-grade students in this school have achieved excellent results in this math exam.
Difficulty: 4. In order to know the final math test scores of 1 0,000 students in a school, the math scores of 1 0,000 students were selected for analysis. The picture shows the histogram of percentage distribution based on the math scores of these 65,438+0,000 students. Answer the following questions according to the conditions given in the question:
(1) Math score (X)75≤X
(2) In this examination, among the students in Grade 8 1000 in our school, the math score is 85 ≤ X.
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Difficulty: 5. The following statement is propositional.
(1) Our eighth grade is full of vigor and good habits.
(2) If x> 1, then -x
(3) Are these two angles equal?
(4) Extend the line segment MN to p 。
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Difficulty: 20 10_ Jining, Shandong 6. A school held a speech contest with the theme "Protect the environment, start with me". After the preliminaries, one student from Grade 7 and Grade 8 entered the finals, and two students from Grade 9 entered the finals. The probability that the first two students are ninth grade students is. The answer set for the question has been shared:
Difficulty: 20 10_ Wuhan, Hubei 7. The weight (unit: kg) of m-girls in Class Two, Grade Eight in a school is 35, 36, 38 and 40 respectively. The median of this set of data is. The answer set is shared with:
Difficulty: 8. In Grade 8 (1), 50 students participated in the "Green Space" written knowledge contest, and 42 students passed. Randomly select 1 answer sheet, and the probability that the answer sheet fails is. The answer set for the problem solution has been shared with:
Difficulty: 9. Students in Grade 8 (1) want to take a group photo during their autumn outing. Each student pays 0.7 yuan money, a negative 0.68 yuan. Each student prints a photo of 0.5 yuan. On the premise of using the collected money as well as possible, there are at least some students in this photo. The answer set is shared with:
Difficulty: 10. In order to know the shoe size of junior high school students, Chaoyun Shoe Factory made the following statistics on the shoe size of 20 boys in Class 2, Grade 8 of Laogumiao Middle School:
Shoe size 23.52424.52525.526 Number of people 344438+0 1
Then the average value of these 20 boys' shoe size data is, and the median value is; Among the average, median and mode, shoe factories are most interested.
1. There are two classes in Grade 8, with 52 students in Class 1 and 48 students in Class 2. Given an exam, the average score of 1 class is 89, and the average score of class 2 is 9 1, so the average score of grade is. The answer set is shared with:
Difficulty: 2. Category 8 (1) randomly selects the number of waste batteries collected on a certain day in the current month, so as to estimate the number of waste batteries collected in April. The data are as follows (unit: section): 48,51,53,47,49,50,52.7.
Difficulty: 3. The picture below shows the score statistics of an exam in the eighth grade of a school. If there are 800 students taking the exam in this grade, the number of students who fail is, and the percentage of students who pass (excluding excellent) in this grade is.
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Difficulty: 4. What do you think is the appropriate way to know the eyesight of eighth-grade students in China?
1. In order to estimate the number of ninth-grade students in the county, Xiao Liang made a survey on the population of hometown and the number of ninth-grade students in the township: the population of the township is about 20,000 and the number of ninth-grade students is 3,000. He concluded that the number of ninth-grade students in the county is about 5250, but the number of ninth-grade students in the county provided by the county education bureau is 3000, which is quite different from the estimated data. According to the statistical knowledge learned,
Difficulty: 2009_ Wenzhou, Zhejiang 2. The school organized seventh, eighth and ninth grade students to participate in a comprehensive practical activity. The fan-shaped statistical chart shown in the figure shows the distribution of participants at the above levels. It is known that there are 80 participants in Grade 9, so all three grades have participated in comprehensive practical activities.
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Difficulty: 20 10_ Jining 3, Shandong. A school held a speech contest with the theme "Protect the environment, start with me". After the preliminaries, one student from Grade 7 and Grade 8 entered the finals, and two students from Grade 9 entered the finals. The probability that the first two students are ninth grade students is. The answer set for the question has been shared:
Difficulty: 4. There are 400 ninth-grade students in a school. In order to understand the eyesight of these students, 20 students were randomly selected and the obtained data were sorted out. It is found that there are 6 students in the range of 0.95 ~ 1. 15, and it can be inferred that the vision of the ninth grade students in this school is 0.95 ~ 65438.
Difficulty: 5. A middle school in Taizhou randomly investigated the age of some ninth-grade students and drew a statistical map of their age distribution (pictured). Then, the probability of a student 16 years old from the ninth grade in this school is.
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Difficulty: 20 1 1_ Yulin, Guangxi; 20 1 1_ Fangchenggang, Guangxi 6. As shown in the figure, it is a fan-shaped statistical chart of the number of students in three grades in a school, and the degree of the central angle of the fan-shaped number of students in the ninth grade is.
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Difficulty: 20 1 1_ Hechi 7, Guangxi. In order to understand the physical condition of ninth grade students, a school randomly selected 30 students, tested the number of sit-ups at 1 min, and drew the histogram of frequency distribution as shown in the figure. The frequency of sit-ups between 20 and 25 times is.
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Difficulty: 20 1 1_ Shandong Zibo 8. Students in Class Two, Grade Nine of a school carried out the activity of "planting trees and greening the city" on Arbor Day. After this activity, the following are some statistics on the tree planting in the class, so the total number of students in this class is three.
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Difficulty: Qingdao Shanghai Special 2009_ Shandong Jinan 9. After learning the lesson "Measuring the Height of Objects", Xiao Liang did the following things in order to measure the height of the kite in the picture:
(1) Set an inclinometer at the kite flying point A to measure the elevation angle c ∠ CBD = 60;
(2) Calculate the length of the kite line BC as 70 meters according to the length of the remaining line in hand;
(3) Measure the height of inclinometer AB =1.5m. 。
According to the measured data, the height CE of the kite is calculated to be about meters (accurate to 0. 1 meter).
The answer set is shared with:
Difficulty: 10, Meishan, Sichuan, 2009. There are 54 students in Class 3, Grade 9 in a school. According to statistics, 18 students participated in reading activities, and those who participated in scientific and technological activities accounted for the total number of students in the class. There are 3 more students who take part in art activities than those who take part in science and technology activities, and other students take part in sports activities. In the pie chart, the central angle of the fan representing the number of people participating in sports activities is degrees.
1.20 10 After the earthquake of magnitude 7. 1 occurred in Yushu County, Qinghai Province on April 4, 60 students from grade 9 of Xiangjiang Middle School (1) enthusiastically donated money. There are 15 people who donate to 30 yuan, and there are 14 people who donate 65438.
Difficulty: 2. Some ninth-grade students in a school do pull-ups, which are divided into four groups. Among them, the proportion of times below 15 is 5%, the proportion of times from 16 to 19 is 15%, the proportion of times from 20 to 27 is 30%, and there are 25 people with more than 28 times.
Difficulty: 2009_ Jinan, Shandong 3. After learning the lesson "Measuring the Height of Objects", Xiao Liang, a student in Class 3, Grade 9, did the following things to measure the height of kites in the picture:
(1) Set an inclinometer at the kite flying point A to measure the elevation angle c ∠ CBD = 60;
(2) Calculate the length of the kite line BC as 70 meters according to the length of the remaining line in hand;
(3) Measure the height of inclinometer AB =1.5m. 。
According to the measured data, the height CE of the kite is calculated to be about meters (accurate to 0. 1 meter).
The answer set is shared with:
Difficulty: 4. The age of 50 students in Class 2, Grade 9 in a school is as follows: age 14 years old 15 years old 16 years old 17 years old 720 167. The probability of randomly selecting a student in this class is exactly 15 years old.
Difficulty: 5. There are 54 students in Class Three, Grade Nine. The Learning Committee investigated the students' participation in extracurricular activities (each student only participated in one activity), among which: 18 people participated in reading activities, 3 people participated in art activities and other students participated in sports activities. The central angle of the fan indicates the number of people participating in sports activities, which is the degree in the pie chart.
Difficulty: 6. The histogram of pull-up frequency distribution of some ninth-grade students in a school is shown in the figure, and the frequency of the third group is 0.25.
Answer the following questions according to the known conditions:
(1) group spacing is;
(2) The total number of students participating in this test is:
(3) If it has passed more than 20 times (including 20 times), the number of people who have passed is.
7. The histogram of the frequency distribution of all students' grades in the math unit test of Class 1, Grade 9 in a school is as shown in the figure (full mark 100, students' grades are rounded), so the frequency of grades in this score of 90.5 ~ 95.5 is.
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Difficulty: 8. A school launched a donation campaign for the earthquake-stricken areas. Eight students in Grade 9 (2) 1 Class donated the following (unit: RMB).
100 50 20 20 30 10 20 15
Then the pattern of this set of data is. The answer set is shared with:
Difficulty: 2009_ Guiyang, Guizhou 9. There are 27 boys and 29 girls in Class 5, Grade 9. When the class teacher issues the admission ticket to the whole class, the probability of randomly selecting a girl's admission ticket is. The answer set is shared with:
Difficulty: 2009_ Zhaoqing, Guangdong 10. The weight (unit: kg) of girls in Class 2, Grade 9 in a school is 38, 40, 35, 36, 65, 42, 42, so the median of this data is.
1. Grade 9 (3) The results of all students' physical education graduation exams are shown in the table below:
The score is lower than 18, 18 ~ 20, 2 1 ~ 23, 24 ~ 26, 27 ~ 29, 30, 23820 12 10.
There are * * * students in this class, and the median is in the fraction section. The solution collection is shared with:
Difficulty: 2. The heights (unit: cm) of four students in Class One, Grade Nine in a school are: 170, 170, 166, 174, so the average height of these four students is cm.
Difficulty: 3. In Class 1, Grade 9, a school made a weekly housework time (unit: hours) statistics for 50 students in the class (calculated by 7 days). The frequency distribution is as follows: the time of doing housework in a week (unit: hours) is 1.522.534+0. 160.
Difficulty: 4. At the New Year's Day party in 2004, 50 students from Class 1, Grade 9 sat together and played the game of delivering packages. Among them, 22 girls and 28 boys were randomly seated. If the time spent in each student's hands is the same, the probability that the flowers will fall into the hands of boys is, and the probability that the flowers will fall into the hands of students whose last number is zero is.
Difficulty: 5. There are 50 students in the ninth grade (1) class of a school. The comprehensive quality evaluation of "sports and health" is shown in the figure, so the number of students in the class with the evaluation grade of "sports and health" is.
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Difficulty: 6. In order to understand the nutritional status of ninth grade students in a school, eight students were randomly selected for hemoglobin detection to estimate the average level of the students in this grade. The results are as follows (in grams):
13.8, 12.5, 10.6, 1 1, 14.7, 12.4, 13.6, 12.2
Difficulty: 7. On May 4th Youth Day, the Municipal Youth League Committee organized some middle school students to plant trees in Xishan. The Youth League Branch of Class 3, Grade 9 of a school received a batch of saplings. If there are 4 trees for each race, there are 37 trees left. If each person has planted 6 trees, and the last person has planted a tree, but there are less than 3 trees, these saplings are * * *.
Difficulty: 8. The head teacher of Class One in Grade Nine took pictures of three graduating students, Xiao Li and Obana Xiaohong. The three of them are randomly arranged in a row to take pictures, and the probability that Xiaohong is right in the middle is.