Mean is a measure of central tendency. It is the average of a set of numbers. It is determined by adding the numbers together and dividing it by the total number
Mean = sum of numbers / number of observation
sum of numbers = 3 x 7 = 21
Median is the number that is at the center or middle of a set of obervations
x + 9+ y = 21
x= lowest number
y = highest number
x + y = 21 - 9
x + y = 12
If x = 1 y = 11
if x = 2 y = 10
if x = 3 y = 9
if x = 4 y = 8
the first 3 are plausible and the median would still be 9 if x = 4, median would be 8
The definition of the inverse property is to add to get a result of zero. Since we are adding the inverse of each term to get a result of zero each time, we are using the inverse property.