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What is the standard deviation in mathematics?
In statistics, we call the whole of the objects to be investigated as a whole, each of them as an individual, and a part of the individuals selected from the whole as a sample of the whole
In a group of data, the most frequent data is called the mode of this group of data
A group of data is arranged in order of size, and the data in the middle (or the average of the two data in the middle) is called the average of this group of data
The so-called "median" is to rearrange a group of data from low to high. By removing the two ends and gradually approaching the center, we can find the value in the middle, that is, the median
Variance is the sum of the squares of the differences between each number in a set of data and the average of the set of data, and then divided by the number of data
That is: [∑ (xn-x) ^ 2] / N, (X represents the average of this set of data.)
The standard deviation is the square root of the variance
Thus, the greater the variance, the greater the standard deviation
A coach conducted a test with a total score of 20 points. The test standard is that the score must be a multiple of 5. He got the following distribution: 40% got 20 points, 30% got 15 points, 20% got 10 points, and the other 10% got 5 points. What's the standard deviation of the score in this test?
(please write down the process,
Eζ=20×0.4+15×0.3+10×0.2+5×0.1=15
Dζ=(20-15)^2× 0.4 +(10-15)^2× 0.2 + (5-15)^2 ×0.1=25
δ=√Dζ=5
I know the formula for calculating the standard deviation is as follows: (where x is the average)
S = (x1-x + x2-x) Xn-x) / n
S=（（（x1-x）^2+（x2-x）^2…… （xn-x）^2）/n）^（1/2）
So I want to ask, how can we introduce Article 2 from Article 1?
In addition, is the statement that the standard deviation is "the average of the distance from the average of the data" correct?
1. Because the score is too few, it is simply introduced. As long as the two standard deviations are completely squared (that is, the variance is obtained), we can deduce that they are equal
2. The standard deviation is the average of the distance from the average of the data
The meaning of the letters in the formula PV = NRT
In the formula of pressure and volume PV = NRT
I know that P is pressure and V should be volume
What do the other letters mean
.
N is the quantity of matter
T is the temperature
R is a constant
Carbon atom is active and can form covalent bond with most element atoms. Why not?
Carbon atom is active and can form covalent bond with most element atoms. Why is this sentence wrong?
Carbon atom is not active, but active at high temperature
Carbon atom is very stable and inactive at room temperature
The meaning of Avogadro formula PV = NRT?
It has the meaning of every letter
P gas pressure
V gas volume
N the amount of gaseous matter
R is a constant
T is the temperature
This formula is very simple to express the relationship between various parameters of gas when it is not used
What is reflexive pronoun? Concept? For example
Reflexive pronoun f à NSH à n d à IC í [reflexive pronoun] is a kind of pronoun that expresses reflection or emphasis. Its basic meaning is: through reflexive pronoun referring to the subject, the actor reflects the action to the actor in form
How to understand the formula PV = NRT?
When I was studying chemistry in grade one of senior high school, I heard other teachers mention this formula, but the teacher didn't mention it. It's said that understanding this formula is helpful for solving problems~
Understanding the CLAPRON equation is really good for doing chemical principles: PV = NRT: for example, when the temperature is increased at constant pressure and constant volume, the total number of moles will decrease, and the equilibrium will move in the direction of decreasing the number of moles. When the temperature is constant pressure, the volume of the reaction system will increase, and the equilibrium will move in the direction of increasing the number of moles Generally, two variables are fixed. When the third variable changes, the change of the fourth variable determines the direction of balance movement. In fact, it's just a scratch, so you'd better ask the teacher!
What is the definition of native place
For example, if a person's native place is a, and his son has moved to B and has n generations in B, then should the family's native place be a or B? What is the minimum value of N?
Place of birth generally refers to your grandfather's birthplace. Take your example, the person's son and grandson's birthplace are both a, and after grandson, they will be B, but their ancestral home remains the same
How to solve problems according to the chemical formula PV = NRT
What is the purpose of this formula? What is the principle? What kind of problems are solved?
Here R is a constant, and everything else can be. Then we can use this formula to calculate the pressure ratio, volume ratio, etc. under the same temperature, pressure, volume or the same amount of matter
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