1. The flexural stress $\sigma$ of a beam with rectangular cross-section under pure bending is given by
$\sigma = \frac{My}{I}$,
where $M$ is the bending moment, $y$ is the distance from the neutral axis (N.A.) to the point of interest, and $I = bh^3/12$ is the area momentum of the cross-section. If $b$ and $h$ have the relative errors of 2% and 3%, respectively, calculate the relative error induced in the maximum flexural stress $\sigma_{max}$ at $y = \pm h/2$ [5 Pts].
