Jiangjunqiao 48 I (excellent)
Champion 66 Inhalable Particulate Matter II (Good)
63 The inhalable particulate matter in Liming West Road is Grade II (good)
Display and analysis II. Qiu Jin Zhongyuan, with deep green shade and rippling lakes, welcomes guests and friends to celebrate the 75th anniversary of Guangdong Zhongyuan Middle School in 2009. In recent years, there are 14 students in Zhongyuan Middle School who won the first prize of comprehensive science province. There are many national and provincial awards in various disciplines ... shining medals, cohesion. Many honors show massiness and tolerance.
The number 2009 also has its special properties in mathematics, just like some natural numbers can be divided into the sum of squares of two natural numbers, such as: 5= 12+22, 13=22+32, 4 1=42+52, 65=42+72. ...
Please discuss: can 2009 be divided by the sum of squares of two natural numbers? If you can, please write it out; If not, please explain why. 3. A research institute will hold a seminar on new mathematics curriculum, and invite * * * 50 front-line teachers to participate. The number of teachers who use different versions of textbooks is shown in the following table: version PEP version A version PEP version B version Soviet education version Beijing Normal University version.
No.20 15 5 10
(1) Two teachers are randomly selected from these 50 teachers, and the probability that two teachers use the same version is obtained;
(2) If two teachers who use People's Education Edition are randomly selected to speak, let the number of teachers who use People's Education Edition A be ξ, and find the variable distribution table and mathematical expectation of random variable ξ. Display analysis 4. There are eight multiple-choice questions in a math midterm exam. Each question is accompanied by four answers: A, B, C and D, and only one answer meets the requirements. Every time students do multiple-choice questions, they are a, b, c and d.
(expressed by mathematical formula). Display analysis 5. If x ~ n (μ, σ), then p (μ-σ < x ≤ μ+σ) = 0.6826, p (μ-2σ < x ≤ μ+2σ) = 0.9544, p (μ-3σ < x ≤
(1) Among the 5,000 candidates, how many candidates scored in mathematics between (100, 120);
(2) What is the admission score if you admit candidates whose math scores are from high to low 1 14? Display analysis 6. Xiaoming doesn't study hard at ordinary times. When he did multiple-choice questions in a math exam, 1 couldn't do it, so he chose an answer at random (4 questions for each small question). The probability of his correct choice is
7. According to the regulations of multiple-choice questions in a math contest, the right one gets 4 points, the wrong one gets 1 point, and the one who doesn't get 0 points or points. There are four alternative answers to each question. If you can't do the problem, can you guess an answer and write it down or give it up? Please explain the reason. 8. In the math exam, each multiple-choice question gave four answers with code names A, B, C and D, but only one of them was correct. If students choose one of the four answers without thinking, then ()
A. the possibility of choosing the right one is high
B. The possibility of wrong choice is high.
C. the possibility of choosing right or wrong is equally great.
D. I can't explain it clearly
Display analysis 9. There are 10 multiple-choice questions in a math exam, and each multiple-choice question has 4 options, of which one and only one option is correct. The grading standard stipulates: "Only 1 item is selected for each question, with 5 points for correct answer and 0 point for no answer or wrong answer." A candidate has given the answers to each question and has confirmed that the answers to seven questions are correct.
(1) the probability of getting 50 points;
(2) Distribution table of the obtained fraction ξ and mathematical expectation. Display analysis 10, (2003? Zhenjiang) It is known that α and β are two obtuse angles. Calculate the value of (α+β). Four students A, B, C and D work out four different answers respectively: 24, 48, 76 and 86. Only one answer is correct, so the correct answer is ().
A.86 B.76 C.48 D.24
Which way?