Math symbols do not show on here, so here is a picture of the equation.
http://img292.imageshack.us/img292/6113/d61544dcef8652d7857bff7ga0.png
a) it is always equal to zero
b) it is always a negative number
c) it is always a positive number
d) it is too difficult to work with
e) none of the above.
2007-01-01 07:55:53 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
and please explain why? if you could
2007-01-01 08:01:18 · update #1
Yeah like #1 said a) it is always = to 0.
Why? Because that is the definition of the mean x-bar: it is the value that solves sum(xi-xbar)=0. The mean xbar is chosen so that the sum of the deviations xi-xbar equals 0!
2007-01-01 08:02:30 · answer #1 · answered by a_math_guy 5 · 0⤊ 0⤋
a) It's always zero.
Think about what the definition of a mean is: it's the midpoint of your data. If you had one value of 10 and one value of 6, then the mean of those two woujld be 8: that mean is exactly midway between the two values. The difference between one value and the mean (2) is the exact opposite of the difference between the other value and the mean (-2). If you added those differences, you'd get zero. This extends to any number of values you include in the set.
Thus, deviation considers the square of all the differences, since this retains informartion about their magnitude but removes any indication about which side of the mean they fall on.
2007-01-01 08:07:48 · answer #2 · answered by TimmyD 3 · 0⤊ 0⤋
a) it is always equal to zero.
2007-01-01 07:59:01 · answer #3 · answered by adrian b 3 · 0⤊ 0⤋