what is the formula for computing the mean?

Question

what is the formula for computing the mean?

Answer 1

There are several types of mean depending on the context or question.  The two most popular are an arithmetic mean which is the average, and a statistical mean which refers to an expected value based on probability weighting.

 

If this is a statistics class, please reply and I can explain a weighed mean further.

 

But to keep it simple an arithmetic mean or average is what is used in most math up to geometry.

The arithmetic mean is represented by the Greek letter Chi with a bar above it, however because the Chi looks like an "X" it is most commonly called "X Bar".  Below is the equation for the mean or X bar.  n represents how many sample values you are given.

 

 

X Bar = x¹+x²+x³....+xⁿ

            -------------------

                     n

 

 

An example makes it easier

 

Find the mean of the following values:  2, 4, 5, 7, 8

 

So we add the values  2+4+5+7+8  and then divide by the number of samples, in this case 5.

 

The Xbar of these values is  5.2.

 

Please let me know if you need more examples of the different means used up through calculus.

 

-Scott

 

Answer 2

 Sum/ numbers.

 

           n

μ  =   ∑   X_i /n = X _{1 +} X ₂ + X₃  +....... X_n

         i=1                     n

 

 

    Example  { 12, 25 , 17)   n =3

  

    μ = 12 + 25 + 17  = 54  = 18

              3                   3