You might be talking about the A Level subject (actually, a part of the subject) "Statistics 2".
descriptive statistics
Examples of descriptive statistics are mean, median, mode, and midrange.
In statistics it could mean the sum of the values for the y-variable.
It cannot be proven because it is not true. Suppose S1 = {0,1,2,3} and S2 = {0,5,10} then S1 u S2 = {0,1,2,3,5,10} then |S1| = n = 4, |S2| = m = 3 but |S1 u S2| = 6 which is NOT n+m = 7
The mean and standard deviation. If the data really are normally distributed, all other statistics are redundant.
In statistics, this is the symbol for the "Variance"
at pluto -- 0.61m/s2 at earth -- 9.8m/s2 mean u can have much high compared to earth
the mean is important in statistics because you will find out your average and can compare that mean to other things..
What do you mean by statistics? Re-Ask the question.
descriptive statistics
no
the mean is affected by outliers
Mean is the average.
Probability/ Statistics
Examples of descriptive statistics are mean, median, mode, and midrange.
The mean is called a non-resistant measure in statistics.
The sample mean is distributed with the same mean as the popualtion mean. If the popolation variance is s2 then the sample mean has a variance is s2/n. As n increases, the distribution of the sample mean gets closer to a Gaussian - ie Normal - distribution. This is the basis of the Central Limit Theorem which is important for hypothesis testing.