finding a sum of a vector without using the sum(x) function

I can make my program give the correct answer using the sum(x) function, but i can't use the sum(x) function. is there a way to use either a for or while loop to accomplish the same thing. my present code is:

clc;

clear all; 

close all;

w = [1,1.2,.8,1];

x = [75, 80, 65, 78];

wa = 75;

for i = 1:1:length(x);

      wa(i) = x(i)*w(i);
  end

sum(wa(1:i)./i)

this yeilds the 75.25 answer that i should get. is there some simple that will fix the sum(wa(1:i)./i) I know that i can use the finite fix of wa(1)+wa(2)+...+wa(i), but i need it to work for any number of indexis of wa. as sum(wa(1:i)) does.

Answer 1

[Sean de Wolski]

Okay code golf:

w*x'/numel(x)

[Matt Fig]

Hole-in-one.

ans/length(x)

Answer 2

[Matt Fig]

If you don't need all of the wa, you should just do a running sum.

w = [1,1.2,.8,1];
x = [75, 80, 65, 78];
wa = 0;

for ii = 1:1:length(x);
    wa = wa + x(ii)*w(ii);
end

wa/ii