Friday, April 8, 2011

Averages The Mean


Mean is the most common way to find average
To find mean, We add all the numbers together and divide it by the total quantity of numbers.
Mean is the sum of all numbers in the data devised by how many numbers there are.
It evens out the 'score' e.g. in an exam if you failed 2 subjects and you scored well in 2 other subjects the better subjects will 'pull up' your average marks
all the numbers
----------------------
no. of numbers
Example : 6,11,7
1st step : Add the numbers 6+11+7= 24
2nd step:Divide the result by the number of numbers ( 3) 24/3=8
So the mean is 8
In a Frequency : Score | Frequency
                                1               2
                                2              5
                                3              4
                                4              2
                                5              1       It says that score 1 occurred 2 times,Score 2 occurred 5 times etc.
So the Mean= 2x1+5x2+4x3+2x4+1x5
                          --------------------------------
                            2+5+4+2+1
                      =  2+10+12+8+5    37
                          ------------------- = ---- = 2.64...
                                     14               14
                                         
                                       

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