Originally Posted by

**ANDS!** Ok well you should be able to construct the scatter plot. That's no problemo.

The correlation coefficient "r" is calculated in a very tedious way if you do not have access to a calculate. It is:

$\displaystyle \frac{n\Sigma(xy)-(\Sigma(x))(\Sigma(y)}{\sqrt{[n(\Sigma(x^2))-(\Sigma(x))^2][n(\Sigma(y^2))-(\Sigma(y))^2]}}$

Does that look awful. Well yes it does. It's actually not really (if you know what all of that means), but I imagine your instructor wants you to have familiarity with the computations here. Here is what I would do:

Create a list on a sheet of paper. In one column write down the X-values. In the other column write down the Y-values. Next to the y-values create another column called "x*y". Then for each pair of data, do just that - x*y. Next to the x*y, do x-squared, and next to x-squared, y-squared. Go down through the list of paired data and perform each line of operations. At the bottom, sum each column up. Once you have done that, all you need to do is take the sum of the columns, and plug them into that ugly equation. Boom - you have your correlation coefficient.

For C., do you know how to determine the line of best fit? It's another ugly bit of equations, but with that column chart, you're just plugging in values. And D., is simply a matter of you using your new equation to make an estimate.