mean is the same thing as average
example
the mean of 30 and 40 is 35 because (30+40)/2=70/2=35
mean absolue deviation is when you take the mean of the set
then you find the diffference of each number of the set then take the mean of that
ex if yo uhave 1,2,3,4,5 and the mean is 3, then ou find the absolute value of the difference of each
|1-3|=2
|2-3|=1
|3-3|=0
|4-3|=1
|5-3|=2
add them and divide by 5
(2+1+0+1+2)/5=6/5= MAD=6/5
