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If a set of data x1, X2, x3.xn is known, the average is a, the variance is B, and the standard deviation is C If we know that the average of a set of data X &;, X &;, X &;. Xn is a, the variance is B, and the standard deviation is C, then the average of another set of data 3x &; - 2,3x &; - 2,3x &; - 2,. 3xn-2 is variance, and the standard deviation is C
If a set of data X & # 8321;, X & # 8322;, X & # 8323;. Xn is known to have an average of a, a variance of B, and a standard deviation of C, then another set of data 3x & # 8321; - 2,3x & # 8322; - 2,3x & # 8323; - 2, and. 3xn-2 has an average of 3a-2, a variance of 9b, and a standard deviation of 3C
RELATED INFORMATIONS
- 1. If the perimeter of a large square is 20cm longer than that of a small square, the difference in area is 35cm2 What is the length of each side of the two squares?
- 2. Parameter estimation problem: let the population obey the uniform distribution of θ - 1 / 2 to θ + 1 / 2, x1, X2 Xn is the sample from the population, and the sample mean is x average Let the population obey the uniform distribution from θ - 1 / 2 to θ + 1 / 2, x1, X2 Xn is the sample from the population. The mean value of sample X and (x (1) + X (n)) / 2 are unbiased estimates of θ. Which is more effective? The key is how to find the variance of (x (1) + X (n)) / 2. X (1) represents the minimum value of n samples, and X (n) represents the maximum value of n samples
- 3. Each classroom is 8.25 meters long and 4.5 meters wide. The floor is paved with square bricks with an area of 0.25 square meters. How many bricks does it take to pave a classroom
- 4. Find ∫ ln [e ^ (x) + 1] / e ^ (x) DX
- 5. Cut the largest semicircle from a rectangular piece of paper 8 cm long and 6 cm wide, and the remaining figure area is () square centimeter
- 6. Given the function f (x) = 2sinxcos (x + 30 degrees) - cos2x + m, find the minimum positive period of function f (x)
- 7. How many different spelling methods are there to make a large rectangle (or square) with 36 squares of 1 square centimeter? (first draw a table and list them one by one, then answer the questions)
- 8. As shown in the figure, the line y = root 3x + root 3 intersects Y-axis at a and y-axis at B. rotate the line 90 ° clockwise around a certain point, and m and N are the opposite points of a and B (M and N are in the first quadrant), the line Mn intersects Y-axis at C and s △ BCM = s △ BMN, and the hyperbola y = K / X passes m and N. calculate the value of K Y = radical 3 · x + radical 3
- 9. Given that z = Z (x, y) is determined by sin (XY) + Z ^ 2 = sin (x + Z), the partial derivative of Z with respect to X is obtained
- 10. Add, subtract, multiply and divide in the five "5", equal to 11! It should be calculated in order, without brackets
- 11. Divide a circle into 16 equal parts to form a short-sighted rectangle. The circumference of the rectangle is 41.4, and its area is
- 12. Find the minimum positive period of function f (x) = 2 (sin2x) ^ 2 + 4sin2x * cos2x + 3 (cos2x) ^ 2, and find the minimum and maximum
- 13. The distance between the two feet of the compass is set at 3cm. What are the circumference and area of the circle drawn?
- 14. 1. On an east-west freeway, there are two cars a and B driving westward. The speed of car a is faster than that of car B, and there is a certain interval between them___ As a reference, car a moves westward and car B moves eastward_____ As a reference, both AB and ab move eastward 2. An object moves in a straight line for 6 seconds. The average velocity in the first 2 seconds is 6 m / s, and the average velocity in the last 4 seconds is 3 M / s 3. The distance between Party A and Party B is 162km. The car starts from place a at the speed of 10m / s. after driving 72km, it drives to place B at the speed of 45km / h. The average speed of the car from place a to place B is calculated 2.3 write the process: known; seek; solve; answer
- 15. The side length of a square lawn is increased by 2 meters, and the area is increased by 40
- 16. Xiaodong has a bicycle with a diameter of about 66cm. If the average speed is 100 cycles per minute, the distance from home to school is 2000m. How many minutes does it take?
- 17. Given that the area of a circle is 78.5cm, the circumference of the circle is
- 18. （2X-Y）²-4（X-Y）*（X+Y）-（X-Y）*（X-1）
- 19. In the parallelogram ABCD, E.F AB.AD And BF = De, BF and de intersect at point P, the bisector angle c of CP is proved
- 20. It is known that, as shown in the figure, a is a point on EF, and the quadrilateral ABCD is a parallelogram with ∠ ead = ∠ BAF. (1) prove that △ CEF is an isosceles triangle. (2) which two sides of △ CEF are equal to the perimeter of the parallelogram ABCD? Prove your conclusion