Recycling concrete aggregate is an important component of green engineering. The strength of any potential material, expressed in terms of its resilient modulus, must meet standards before it is incorporated in the base of new roadways. There are two methods of obtaining the resilient modulus. The exterior measurement \(M_{\text {ext }}(\mathrm{MPa})\) and interior measurement \(M_{\mathrm{int}}(\mathrm{MPa})\) can be measured on each sample. The results for \(n=9\) samples are (Courtesy of Tuncer Edil)

(a) Draw a scatter plot to verify the assumption that the relationship is linear, letting \(M_{\text {int }}\) be \(x\) and \(M_{\text {ext }}\) be \(y\).

(b) Fit a straight line to these data by the method of least squares, and draw its graph on the diagram obtained in part (a).

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Mext| 204.7 184.8 181.1 166.5 165.2 154.1 135.8 173.4 142.7 Mint 707.1 632.2 603.6 522.4 554.4 483.5 449.7 545.1 473.8