$\text{EFGH}$ (solid lines) is the initial configuration and $\mathrm{E}^{\prime} \mathrm{F}^{\prime} \mathrm{G}^{\prime} \mathrm{H}^{\prime}$ (dashed lines) is the deformed configuration of an object as shown in the figure. $\mathrm{E}^{\prime}$ coincides with $\text{E}$ and $\mathrm{F}^{\prime}$ coincides with $\text{F}$.
The average normal strain along the line segment $\text{OP}$ is $\_\_\_\_$ (rounded off to three decimal places).
Figure is not to scale.
All units are in $\mathrm{mm}$.
