Strategic Management relates a study in economies of scale in the paper industry. the data is found in the following table.

x

$50$

$60$

$73$

$82$

$90$

$215$

$230260$

y $1\mathrm{.}81\mathrm{.}61\mathrm{.}51\mathrm{.}250\mathrm{.}950\mathrm{.}600\mathrm{.}500\mathrm{.}54$

Here x is the weighted average machine size in tons per hour, and y is the employee$-$hours per ton.

A$.$ Determine the best$-$fitting line using least squares and the square of the correlation coefficient.