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Here is the question: You are given the following for a sample of five observations from a bivariate distribution:

x y

1 4

2 2

4 3

5 6

6 4

x(with a line on top) = 3.6, y(with a line on top) = 3.8

A is the covariance of the empirical distribution F(underscore e) as defined by these five observation.

B is the maximum possible covariance of an empirical distribution with identical marginal distributions to F(underscore e).

Determine B - A.

What does the line on top of a variable mean?

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In this context $\overline x$ and $\overline y$ are the mean values of $x$ and $y$, i.e., the ordinary arithmetic means of the five values that you’re given. –  Brian M. Scott Dec 11 '12 at 11:12
Oh, so they are. I thought they were giving me new information. Thanks! –  Eliyahu Dec 11 '12 at 11:24
My pleasure. $\,$ –  Brian M. Scott Dec 11 '12 at 11:25

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