##### Statistics

Human beings since they have started social life, developed various tools to gather and analyse data. There is some of them wchich you will need during math lessons:

arithmetic average

###### arithmetic average

is the sum of a series of numbers divided by the count of that series of numbers.

###### Weighted Average

is a calculation that takes into account the varying degrees of importance of the numbers in a data set. In calculating a weighted average, each number in the data set is multiplied by a predetermined weight before the final calculation is made.

###### median

is the middle number in a sorted, ascending or descending list of numbers and can be more descriptive of that data set than the average.

###### Mode

is a number which appears most often in a set of numbers.

###### Growth chart

is a trigonometric function that for an acute angle in a right triangle is the ratio of the side opposite the angle to the hypotenuse.

###### Standard deviation

is a statistic that measures the dispersion of a dataset relative to its mean and is calculated as the square root of the variance. The standard deviation is calculated as the square root of variance by determining each data point's deviation relative to the mean.

##### Probability

Human beings also wanted to predict results of random events. Great example of a random event is rolling the dice, so we will present some probabilty theory based of this example:

- ###### Probability

  Probability of an event is a number that indicates how likely the event is to occur. It is expressed as a number in the range from 0 and 1, or, using percentage notation, in the range from 0% to 100%. The more likely it is that the event will occur, the higher its probability. The probability of an impossible event is 0; that of an event that is certain to occur is 1

  To calculate probability of some results of a random event we can formula:

  P(A)=
  A

  Ω

  Where:

  P(A) is a probability of event

  A is a number of elements in event collection

  Ω is a number of elements in Sample space

- ###### Sample space

  is a collection of possible outcomes of a random experiment e.g.

  Ω = [1,2,3,4,5,6]

- ###### Event

  is the collection of some outcomes of an experiment e.g.

  event A - only even numbers
  A = [2,4,6]

- ###### Example

  To count Probability of throwing with dice an even number, probability formula(describe higher) can be used.

  Where:

  P(A) is a probability of event A(declared higher)

  A is a number of elements in event collection A(declared higher)

  Ω is a number of elements in Sample space(declared higher)

  Then, substitute letters with real numbers:

  P(A)=
  3

  6
  P(A)=
  1

  2

  Probability for throwing with dice an even number is 0,5(50%).