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Simple Statistical Concepts

Statistics is a set of tools that can be used to obtain answers to important questions about data. It is generally
considered a prerequisite in the field of machine learning. We need statistics to help turn observations into information
and answer questions about observation samples.
Central tendency is expressed as a summary of a data Measures of Central Tendency
set in a single value, representing the entire distribution
of a data domain (or data set). Central tendency does
Mean Median Mode
not analyse the individual values in the data set but
provides a complete summary of the entire data.
Mean

Mean is an essential concept in statistics. The mean is the average or the most common value in a group of numbers.
The mean is the sum of all the values divided by the total number of values.
Formula
Sumofobservations
Mean =
Total numberofobservations
x + x + x ++ x
...
x= 1 2 3 n
n
Where,
u x = Mean
u x , x , ..., x = All the values in the data set
n
1
2
u n = Total number of values
MEAN (Individual Series): Direct Method
Wages 1. Find ∑x by adding all the values
(x)
∑x = 1500
100 2. Find total number of items (N)

200
300 N=5
3. Apply formula
400
∑ x 1500
500 X = = = 300
N 5
∑∑ x = 1500

MEAN (Discrete Series): Direct Method
(Frequency Array) 1. Find fx

Wages 2. Find ∑ fx and ∑ f
(x) f fx 3. Apply formula
100 2 200 X = ∑fx = 3000 = 300

200 1 200 ∑f 10
300 3 900
400 3 1200
500 1 500
∑ f = 10 ∑ fx = 3000

Mathematics for AI 135